If you can’t respect your customer, or can’t do business with your customer without feeling some sort of contempt for them, then you probably shouldn’t be doing that business, because you probably won’t be very successful in the long run.
In this particular case. If you really think the rental pool is “trash” and if “trash people” really bother you, well then you probably shouldn’t be doing this.
It won’t take much to push you over, or say something or do something to get in hot water.
Besides life is too short to spend your time dealing with people you don’t like. It’s not like you desperately need the extra income. Or get someone to do it so you aren’t so attached to it.