Bogus by-laws, sneaky shut-outs and even vandalism could be used to keep holiday lets out of apartment blocks that don't want them, say Sydney's building managers.

And should the NSW government change the law and force apartment blocks to accept short-stay rentals, such as those booked via online agencies like Airbnb and Stayz, strata schemes will find ways of blocking them.

In fact, they are already doing it.

"Any apartment block that really doesn't want holiday lets can stop them, regardless of what the law says," said the on-site facilities manager of a city centre building, who asked not to be named.