What your describing is nice but at least the guy knew there was going to be a sale..

If they are deemed responsible have them pay now out of pocket, or worst case you cover it and come up with a written payment plan for it (but ask an attorney about that for sure).Too many people use their deposit as last month's rent at move-out even when they're not supposed to, and now you have past damages (this incident) and any potential move-out damages or costs that have not been covered. 

Not nice to try and fool Mother Nature aka Karma.

They mow the lawns, (most suck at it) and they must do it or get written up.

I am also considering selling the property next spring so this would be the last lease and I don't to play nice. 

You could give them a final notice, a written warning that you are done accepting late payments.

It may sound nice to pay a 6% management fee but the extra fees can add up to be more than the other company that charges 10% with no additional fees.

I mail a brief, hand written letter where I introduce myself.

I will say we generally have no trouble keeping ours full and we focus on having nice, clean, safe spaces.

My guess is 99%+ of agents have no familiarity with off-market deals or the real nuances of the laws, they do exactly what their brokerage tells them to do with appropriate checklists and pre-written forms/contracts.