As more investors and landlords move to list houses and apartments on short-term rental websites, like Airbnb, rather than seek long-term renters, a fight is emerging over the impact this shift has on renters.

Earlier this year, a group of Democratic senators asked the Federal Trade Commission to investigate whether Airbnb and other short-term rental sites are making housing more expensive in certain communities, and/or placing some units completely out of reach except for short-term renters.

In the September issue of HousingWire Magazine, our own Kelsey Ramírez wrote a feature story on the impact of Airbnb in New Orleans and asked whether the short-term rental industry is going to disrupt the entire housing market. For more on that story, click here.

A new report from Bloomberg furthers that point, and shows just how contentious the fight over Airbnb is becoming in certain expensive markets, like San Francisco.

As these types of fight always do, lawyers are involved. But it’s not just lawyers, private investigators are involved too.

Here’s Bloomberg’s David Levitt:

In a gentrifying neighborhood of San Francisco, a couple exit their cab and head toward an apartment, rolling suitcases behind them. Unbeknownst to them, a private investigator by the name of Michael Joffe sits in his parked car just across the street, discreetly snapping pictures.

This is not a divorce case waiting to happen or an international spy caper. Nothing that salacious or mysterious. It is instead an episode that provides a window into how bitter the feud between struggling tenants and home-sharing websites like Airbnb Inc. has become. Joffe works for a tenant lawyer who in turns represents a family that was evicted from their apartment -- the one that the couple was entering that day.

The goal of the stakeout was to uncover, and document, smoking-gun proof that the landlord is violating city ordinances limiting the use of private homes for short-term rentals. It’s very lucrative work nowadays in San Francisco, the city that’s come to represent America’s shortage of affordable housing.

“Unfortunately, or fortunately, depending on how you want to look at it, it’s a decent living in San Francisco right now being an investigator doing these kind of jobs, because here are so many of them,” Joffe, 48, said.

At issue is whether some landlords are booting long-term renters out of apartments to list those units on Airbnb instead.

Why? Because there’s more money to be made, of course.

Here’s Levitt again:

A group of New Orleans-based volunteers published a paper that found that the average rent on an entire home on Airbnb in that city was $251 a night, compared with an average of $26 a night for a full-time renter.

Click here (or below) to read the whole article on Bloomberg.