I have had many rentals for many years, and I used to accept pets. But after a while I realized it was just not worth it. Getting the units handed back to me with pet damage just got to be too much. And every prospective tenant claimed their dog was trained, not a barker, and they would of course take good care of the unit. I may be a slow learner, but eventually the evidence just became overwhelming.
As to the common assumption that cutting your prospective rental pool in half (approximately) by not allowing pets hurts one’s rent levels and bottom line–the opposite may be true. Some tenants actually want a pet-free environment. They may be tired of barking dogs and poop on the lawns and be seeking out my kind of apartment complex. Accordingly, my Craigslist ad actually says “Sorry, no pets allowed in these clean and quiet buildings.” Don’t know if I gain more prospects than I lose from such a policy.