AirBnB market the idea that someone rents out a spare room/apartment for a couple of while they're on vacation. In general, this isn't something people would complain about.

The reality, of professionals renting out multiple apartments for the whole year, is when the neighbours will complain: there's the noise of 50-100 people clunking their wheelie suitcases in and out, not knowing where to take their rubbish and leaving it in the stairwell, having a noisy party, etc. Plus, a feeling of reduced security when there are unfamiliar people in the building all the time.