Keepin' the "Bad Guys" and gals..out

Ok, someone in park tells you they are selling their home,you give them the proper forms for new owner and preach to them the new owner must fill out application and return for approval. The seller doesn’t give a hoot about you, they see some money and are gone in a flash selling to anybody that has even a portion of their price up front. Nine times out of ten they are someone to whom you would not approve. keep this

What procedures do you follow to process in your favor?