I feel the approx $1000/annual cost is well worth it for the representation at a state legislation level, advertising, and use/credibility of the word "Realtor".

Once the banks realize the house has been sold, they then can enforce the due on sale clause.

You also better make sure you enforce it... otherwise it's pointless.

If you do not enforce your rental agreement and have to go to court, the judge will look at how long it took for things to go bad and allow the tenant the same amount of time to correct. 

We had horrible tenants we had to evict that called code enforcement hoping they could stay (even though they weren't paying).

You should check with your state's landlord/tenant laws to make sure you're doing things correctly when getting into landlording, but the lease (if there is one) should be enforced on the new owner in a sale situation. 

search the dade county code enforcement sites (there are multiple).If you're a smooth talker you might be able to call them and find out about it (however alot of the code enforcement people are completely useless...).If you need help searching liens,code enforcement ,etc..

Wouldn't this be hard to enforce?

If they are VERY professional, they will have their processes in writing as verification that it is enforced equally and fairly by their entire staff. 6.

(Obviously tough to enforce, especially if they have pets, etc) But I guess you could show that their actions are causing yo u damages and take them to court.