The political rhetoric fired up quickly after the Chargers released their downtown stadium initiative last week, so let’s begin our quest for clarity.

Here’s the short version: If it passes in November, the initiative will protect the team’s business interests for 30 years or more, and leave plenty of unanswered questions for taxpayers.

This is not surprising, because the Chargers wrote the thing. Besides, they enjoy major leverage — a deal with the Rams to share the mighty Los Angeles market if San Diego voters turn them down.

Speaking of voters, there’s no sign that Mayor Kevin Faulconer or any other elected leader negotiated for the public while the Chargers were drafting the plan. This absence of advocacy shows in the document.

However, none of this means the Chargers initiative is necessarily a bad deal for San Diego. It could even look like a good one, depending on your perspective.

That’s because building NFL stadiums outside the nation’s largest cities — and expanding convention centers, for that matter — usually don’t turn out to be good financial or economic investments. If they were, private developers would be happy to build them, no tax hikes required.

It follows that voters should weigh such projects based primarily on whether they want them, period. If people think keeping the Chargers in town is worthwhile, especially if the stadium design is cool and they win a few games before Election Day, then voting “yes” might make sense, all by itself.

Besides, the plan taxes visitors instead of San Diego residents.

At the same time, it’s sensible to consider the costs. So let’s dig into some of the details, some of which seem deftly buried.

For openers, the 110-page document does not include the word “Chargers” even once. Instead, San Diego voters are asked to raise the tax on hotel stays so that a “professional football team” can lease a publicly owned stadium that is “designed to be integrated into a convention center expansion.”

Notably, the initiative also is silent on the projected cost of the complex. Instead, it says the “private sector” will contribute $650 million, while the higher hotel tax will fund $350 million, both toward construction of the stadium portion.

Such euphemisms are encouraged by state law, which prohibits local voters from nakedly sending tax dollars to any one private company.

Yet that’s precisely what this is, of course. The Chargers want to raise a tax so they can cut their costs for a new, profit-maximizing stadium. Can you blame them?

Without more details, we are left to use our calculators to infer much of the rest. Conveniently, the team’s financial advisers have done much of the work, which you won’t find in the legal document.

The initiative would pledge 5 cents of each dollar of room rates to cover bond debts. At an interest rate of 6 percent over 33 years, this would finance $1.15 billion in bonds to provide $600 million for the convention center; $200 million to buy land and move a bus yard; and the $350 million public share of stadium construction. Taxes would also back up $25 million each year for operating and maintenance, plus $4 million into a capital repair and improvement fund (both rising with inflation).

Let’s pause to reflect: This is a very conservative model. The Chargers want to make sure the stadium is built and maintained, and that they don’t get stuck with a bankrupt stadium partner.

For one thing, interest rates on public debt are closer to 4.25 percent than 6 percent so debt service would be lower, although that could change by the time construction starts, probably after 2020. For another, the model assumes that hotel taxes will grow by 4 percent a year. Even with the Great Recession, the historical average is higher at 4.6 percent annually.

What’s more, the assumptions don’t include growth in the number of hotel rooms. For perspective, nearly 1,500 rooms are under construction within San Diego city limits, and thousands more are in various stages of development.

This conservative model is good for filling city potholes and pensions to the extent it raises the odds that cash will be left over for the general fund. Indeed, the model forecasts $51 million a year by 2036 that could flow into unrestricted city coffers.

Then there’s that other bright side: The public’s contribution would come from boosting the tax on hotel stays.

It’s always easier to tax outsiders than locals, and this particular plucking could finance more than $1 billion for construction, plus preserve $36 million a year for tourism marketing that grows with room-rate inflation.

Some local Republicans, joined by hotel owners, objected last week that raising hotel taxes would hurt the economy. They are right, but only barely.

Raising the average property’s cost of a hotel room by 1 percent reduced demand for overnight stays by just 0.13 percent, according to a careful study of urban hotels in 22 top metropolitan markets (including San Diego) by Cornell University professors Linda Canina and Steven Carvell published in 2005.

Far more important than cost is what happens to incomes and the economy. The study found that when corporate and personal incomes rose by 1 percent, the demand for room nights increased by 0.41 percent.

So to potential travelers, income is roughly three times more important than cost. This helps explain why San Diego hoteliers have been able to boost their revenue per available room by roughly 7 percent a year since 2011, a period of economic growth, without snuffing out demand, as well as why revenue plunged 20 percent in the 2009 recession year.

For context, the Chargers plan would raise hotel taxes to 16.5 percent. Just a few years ago, the hotel industry orchestrated its own hike to 15.5 percent, a portion of which was later ruled illegal.

If hotel owners oppose the Chargers’ initiative, it’s more about disliking the project’s location and the city’s control of marketing money, and not the tax itself.

Yet the Chargers’ plan also offers them an olive branch. One provision gives the city explicit permission to pull surplus money from the stadium authority, and use the cash flow to finance future convention center projects, as long as debt service and other obligations are covered first.

This might pacify hotel owners who would rather expand along the bay than build a new center near Petco Park, the site of the Chargers’ proposal. On the other hand, it invites conflict with former Councilwoman Donna Frye and attorney Cory Briggs, who’ve sponsored another initiative that would bar bayside expansion.

The team’s initiative has other provisions that may draw opposition.

In the “private sector” contribution, for example, we see the team’s L.A. leverage on display. In low-cost Minnesota, the Vikings are paying $630 million toward their $1.1 billion stadium, whereas the Chargers offer $650 million toward a stadium that, we’re left to infer, would cost just $1 billion in high-cost San Diego. It’s easy to suspect some stadium cost will shift to the convention center and land acquisition side of the ledger.

To belabor the comparison, the NFL also has offered a $100 million grant in San Diego that the Vikings didn’t get. Still, the Chargers may not get to pocket all this difference, because their initiative puts them at risk for stadium cost overruns, once they’ve agreed with a stadium authority on the allocation.

Then there’s the question of rent.

The document punts lease terms to the future for the Chargers and the stadium authority to work out each year. The language requires the team to pay for game-day costs.

For the overall stadium, the first $15 million a year for operating and maintenance comes from the authority (which also would pay $10 million for the convention center). On the plus side for taxpayers, the Chargers are on the hook to keep the stadium spiffy beyond that amount.

Less clear is language that allows lease pre-payments to count against the $650 million “private sector” contribution toward construction. One interpretation limits advance payments to sales of seat licenses, stadium naming rights and the like.

Still, lawyers and accountants could end up fighting over whether the team can claim millions of dollars in advance rights payments for stadium concessions, given that the same company will pour beer for football fans as well as concert audiences.

I’m not suggesting a big gotcha here. After all, the Chargers are offering $650 million toward a stadium they will use 10 days a year, maybe 13 if they reach the playoffs or land a Pro Bowl or Super Bowl. And the initiative requires the stadium authority and team to agree on which costs and revenues will count toward the convention or stadium — before construction starts.

Incidentally, the team’s deal with the NFL requires them to decide whether to leave San Diego by January 2017, or opt for a one-year extension if the initiative passes.

This brings us to perhaps the greatest uncertainty: The initiative asks voters to trust that city government will run a new stadium and convention center more effectively than it has operated its old ones, which lose millions of dollars and get shabbier each year because the politicians generally don’t care about upkeep.

Sure, the Chargers’ initiative would ensure the complex isn’t starved for cash, and the team would control stadium upkeep. But booking and running the convention center is left to government.

Even getting to construction will require highly competent city management, because so many crucial decisions would be made in the first year.

Setting aside those critics convinced the Chargers plan amounts to picking public pockets, voters must also decide whether they can trust their government to pull this off.

dan.mcswain@sduniontribune.com (619) 293-1280 ▪ Twitter: @McSwainUT