No deposit is required!

It is very common in CRE to bait and switch or have a loan denied and paying $2k+ for an appraisal and a 1% deposit. 

No deposit is required!

But the damage caused by hanging them (namely puddying the holes and touch up paint, or repainting walls if touching up doesn't work) will come out of their deposit. 

Consider all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

However, when someone breaks a lease early, they are often not in a financial position to pay those, so you can apply their deposit to those costs, and after that, good luck.  

Are you depositing your pay in the bank?   

I built into my analysis of each property monthly deposits into that account to cover those contingencies.  

If I think about canceling the contract, I am very sure I'll not get the 10% earnest deposit I already paid.

It has to be secured before we can close, the reason we have requested a 50% deposit and other balance paid once closed.