The thing about political waves is that they sweep in sturdy and rickety boats alike.

Case in point: Progressives currently are so excited about their fresh faces supporting universal healthcare and a $15 minimum wage that they haven’t noticed some of the serious flaws that threaten to derail this new crop of left-wing heroes.

Take the case of Andrew Gillum, the mayor of Tallahassee who just stunned the political establishment by winning the Florida Democratic gubernatorial primary on Tuesday. Lost amid the hoopla over his unexpected win was discussion over the fact that the city he runs is currently embroiled in an ongoing F.B.I. investigation into allegations of corruption. Gillum insists he is not a target of the investigation. And that seemed sufficient in the Democratic primary where, as the Tampa Bay Times reported last month, his opponents (perhaps because he never seemed like an actual threat to win) didn’t really bring the issue up.

But it ain’t gonna go unnoticed in the general. Florida Democrats may well have blown the governor’s race without realizing it.

Then there is Keith Ellison, congressman and deputy chairman of the Democratic National Committee, who was accused of abusing his ex-girlfriend just before winning his primary for Minnesota Attorney General. Ellison’s defenders noted that the woman’s story had been explored (and largely ignored) by local press. But because the allegations came during the eleventh hour of the campaign, the issue was not truly processed by the voters. They will certainly have time to consider it now, with outlets like the New York Times doing deep dives into the matter. And that may not be great news for Ellison or other Democrats in the state. As Politico reported, “Last week, the Congressional Leadership Fund, the main super PAC backing House Republicans, launched ads attacking Democrats in four House races for refusing to rebuke Ellison.”

Meanwhile, in neighboring Wisconsin, the Democratic nominee for the House seat being vacated by Paul Ryan is Randy Bryce, whose “IronStache” viral video made him a progressive rock star. Bryce has raised more than $6 million thus far in his campaign. The only problem is that he has a laundry list of previous arrests, including one for driving under the influence. Democrats forgave it all, elevating Bryce over a progressive teacher in the primary. Will a larger electorate be as forgiving?

In a year when Donald Trump’s behavior seems so egregious, and when Democrats seem so poised for victory, it seems surprising that Democrats are fielding so many candidates with so much potential baggage.

But the problem isn’t merely that progressives might be nominating embarrassing candidates who will lose elections. Democrats are also at risk of nominating embarrassing candidates in deep blue districts who will win elections. Alexandria Ocasio-Cortez is a lock to win her New York Congressional race, but she is also in danger of becoming a laughing stock after a series of interviews exposed her lack of policy depth.

There’s also the danger of electing a crop of progressives with questionable or problematic stances. J Street rescinded their endorsement of Rashida Tlaib once it became know that she supports a “one state solution” to end the Israeli-Palestine conflict. It was too late, as she had already secured the Democratic nomination for her Michigan congressional seat. Likewise, Democratic nominees like Scott Wallace, the grandson of former Vice President Henry Wallace who is a Democratic nominee for Congress in Pennsylvania, helped promote anti-Israel boycotts. And Leslie Cockburn, a Democratic nominee for the House in Virginia, faces charges of anti-Semitism over a book she co-authored decades ago.

I’ve seen this movie before. A decade ago, mainstream conservatives (including yours truly) cheered as John McCain picked Sarah Palin as his running mate. Two years later, the Tea Party zeitgeist swept in Republican nominees like Marco Rubio in Florida, but it also gave us political losers like Sharron Angle (Nevada), Todd Akin (Missouri), and Christine O’Donnell (Delaware).

With fewer crackpots, the GOP could have won the Senate in 2010 (which would have resulted in many fewer federal judges appointed by Obama).

But that was just the beginning. The Republican establishment thought they could co-opt and contain the populist energy that started in the Tea Party. They were wrong. What started in 2010 eventually led to a motley crew of weird and/or sketchy candidates like Ben Carson, Paul Nehlen, Roy Moore, and Joe Arpaio―and, yes, Donald Trump.

It is understandable that progressives are excited about this fresh crop of young true believers. They may not be as far out there as O’Donnell (who famously had dabbled in witchcraft) or have said things as wild as Akin (infamous for describing “legitimate rape”). But I would still caution progressives about the sort of hero worship that elevates candidates who aren’t ready for prime time.

Often the most fresh and charismatic candidates are the most eccentric and unproven. For ideologues, toughness and purity covers a multitude of sins. But don’t skimp on vetting for experience and for character.

The heart wants what the heart wants, but resist the temptation to fall in love with any politician. Such unthinking endorsements can lead to some scary places. In some cases, they already have.