No offense intended but you look very young in your picture, do you have a credit history/score?

Maybe their criminal records stop them from getting licensed LOL!!!

Criminal and eviction is pretty self-explanatory but you should develop a policy about what crimes justify denying someone and which ones don't.

You could be criminally liable if there is a fire and building is used as unlawful 4 unit rental (similar to Ghost Ship fire). 

A person found smoking in a public place, or the owner who fails to post or supervise the implementation of a smoke-free public place, shall all constitute a separate offense and enforcement actions for violations may be brought against any person smoking in a public place, the owner of a public place, or both.

This guy had no criminal history, good credit and a stable job for 10+ years.

Of course, running their credit and criminal could well give you an indication as to why they're offering such an amount of money up front. 

All purchasers of rental property should independently contact the municipality where the rental property is rented to verify (at a minimum):  1) rental license valid and what tier (if exists), 2) any open work orders on the property and when was the last inspection, and 3) any criminal activity at the property (public data request). 

I don’t take any offense.

When a decent mobile home comes on the market (usually around $25,000 - $35,000) people are chomping at the bit to purchase.Cities are killing off mobile home parks because they don't produce much in sales tax, are generally unsightly, and have high potential of turning into a haven for criminals.