Just make sure you can prosecute those that test you. The leases I have and properties I hunt ALL have "zero tolerance" enforced. You will reap a few "haters" ......and reap many "non-testers" ....... And as for the "haters".....they were going to hate you anyways whether you had a zero tolerance stance or not. I'd rather force their hand to be known.......
Just remember......your not leasing "to make new friends" in most cases.
"A good fence makes a good neighbor".