Once we realized that the grass is not greener on the other side, the damage has been done, and it has set us back a decade.

If your tenant's rent deposit ends up going on utilities and there is damage to the unit you can end up coming out of pocket. 

Sounds like in the past people were all cash buyers but didn't put up much earnest money and backed out damaging the seller.Even when you put in no contingencies many buyers are flaky.If the purchase was for say 60,000 and you put up 30,000 non-refundable money that gives the seller the warm fuzzies that no way you will back out.

Having already been through this before I know they will hit is for missing siding, the whole said of the front building needs to be re-graded, the roof needed replacement and is causing water damage.

You can charge any damage. 

If the roof is badly damaged or worn out then I would replace it with asphalt.

Collect a pet deposit, but remember that a "pet deposit" termed as such can only be used for pet damage and not just any damage. 

You can also be doing him a favor having the matter corrected now instead of later on when he gets involved in a closed transaction with other issues, where he could lose his license and be hammered with fines or damages.

I have yet to find one that is willing to damage their reputation by sending out a lot of lowball offers they don't think will get accepted.I have moved away from the idea of a buyers agent.

As a builder I can tell you that until you get into a property, and start doing the work, you can have an idea of what needs to be done, but never know for sure the extent of things like water, termite damage, structural defects, bad wiring, etc. that you're working with, and there can be costly surprises if the house isn't inspect thoroughly beforehand.