Brian McConvey has watched condo buildings dwarf the townhouses that once stood alone in Liberty Village when he moved there 12 years ago. With the condos came more renters and now, more and more people using Airbnb.

The surge has turned McConvey into a sleuth. His goal is figuring out who is running short-term rentals in his condo and reporting them to management, which has rules against those types of rentals.

He says the Airbnb users are easy to spot.

"The Italian family with their kids and their suitcases, or you see a bunch of guys ... people come in for the weekend to go to a soccer game," he told CBC News.

The condo owners renting out their units via the popular online platform "know they're wrong," he said.

A quick search on Airbnb reveals hundreds of rentals in Liberty Village — including many that go for around $200 a night. That neighbourhood, as well as the waterfront and the Yonge and Church areas, is considered one of the city's "hot spots" when it comes to short-term rentals, according to a recent Canadian Centre for Policy Alternatives report.

The study says 64 per cent of the the places available in Toronto are entire homes or condos, which would typically be considered attractive rental properties. Realtors say this shift is changing the marketplace and could spell trouble for some homeowners.

Airbnb 'an epidemic' in Toronto

Realtor Brad Lamb says he frequently hears from people who bought condos and rented them out, only to discover they're being offered up as short-term rentals.

"This is an epidemic," Lamb said, adding some renters are treating their places like hotel suites.

If they were earning $3,000 a month on that rental, now they're renting it out for $300 a night. - Realor David Batori

He says owners are often unaware and when they find out, getting a tenant evicted for running a short-term rental proves extremely difficult.

David Batori, a realtor with more than a decade of experience, says he often works with clients who want to buy condos to rent out, but now more than ever they're looking for short-term rentals rather than year-long leases.

"They tell me how they have very good returns on their properties compared to when they had annual tenants on them," Batori said.

"If they were earning $3,000 a month on that rental, now they're renting it out for $300 a night. It's not rented every day but if it's rented for 20 days out of the month they've doubled their monthly return."

City studying issue

Mayor John Tory says this is an issue he's hearing about every day and one he was just discussing with Calgary Mayor Naheed Nenshi.

In Toronto's case, Tory said, "we have a report coming this fall about the implications of the issue and what we might consider doing about it."

Tory says hotels with condo units in the same building have contacted the city to complain about the lack of oversight. He says the hotel owners are particularly upset that they pay fees to the city but that the short-term rental market is unregulated.

Toronto Centre-Rosedale Councillor Kristyn Wong-Tam says any new guidelines the city comes up with won't be about targeting Airbnb. She said it's crucial the city come up with "clear regulations" to make sure the city is liveable, affordable and sustainable.

"The tipping point is already here," Wong-Tam said.

Trish Hennesy, co-author of the CCPA study, says Airbnb hosts with multiple properties account for a small percentage (13 per cent) of more than 10,000 units on that website. But she notes that's still significant in a city with a low vacancy rate for apartment rentals.