Blacklist, that might bring you legal problems.
But the sharing of information is a good idea. That is exactly what the Credit Managers Association does in regards to commercial accounts. One member may get burned by the subject company finds all doors closed with legitimate suppliers.
I say monthly business meetings might be a good idea. Form an association. Have an agenda. Heck, you can talk about the newest annoying dweeb that is giving the industry a bad name. No liquor, have lunch after the meeting. Make a morning of it. Cleaners who know each other might be less likely to stab each other in the wallet.
Just my thoughts on the subject.