If your numbers are off or unexpected expenses come into play, 2% gives you no wiggle room.

There’s no cushion for cost-overruns, softening in the market (thus a lower sales price and increased DOM), or any other unexpected hiccups that ALWAYS occur.  

Things happen unexpectedly and you want/need reserves to cover your expenses.

No one can predict the future so you have to prepare for the unexpected.

I would also ask about hidden fees or unexpected fees. 

I've had plenty of owners loose an amazing tenant because they had to get $60 extra on the lease renewal instead of accepting $50 or thought we should help out with the cost of a new furnace because it was unexpected and they already pay us every month. 

Otherwise known as Component Depreciation ;). 

All major components are needed.

So if something unexpected is uncovered during due diligence I can't get the deposit back. 

You want an emergency fund to cover the unexpected.