Whether I kept them or not would depend on how well they're maintaining the property--when you go check things out, is the place a complete disaster? Are the dogs chewing the trim? Does the place stink? Are you going to end up with $1000 worth of repairs when they leave? If so, I'd boot them, otherwise I'd stick it out. If they want you to install a water softener, just say no, and leave it at that.