I'm a newbie also, and like you, find it cathartic folding clean laundry...and even washing dishes.

also, I added, Animals/Fish will not be cleaned on the property. 

Plus cleaning fees, and pet fees.

It all seems so clean and simple...so why doesn't anyone else do it? 

I think with the lease and local laws I can find a easily justifiable way to pin this to both their backs, but I'll trade my right to leverage terms for a clean break and ability to move on.  

Clean the yard at your expense.

In light of that $650 seems reasonable if your units are updated, clean and frankly somewhere you'd live without thinking twice about it. 

Brokers like things to be clean and easy (this is not a slight to brokers at all) without much potential liability.

@Jessica Mendez please see https://www.cdc.gov/mold/Also, one of the best and non-caustic/non-toxic ways to remediate mold is commercial grade Hydrogen Peroxide...safe and penetrating...https://www.reference.com/home-garden/hydrogen-per...http://greenopedia.com/clean-mold-without-bleach/

They seemed ideal, they paid rent early and kept the place reasonably clean.