I will put carpet down if that's the only option.

New carpet or sand/refinish the hardwood. 

Their place was very messy, crap all over the floor throughout the house. when I walked in she was laying on the couch and watching TV and tilted her head and said hi (that's only after I said hi) and continued watching TV, still laying down. 

For your first one, you might want to get something like a 2 or 3 bedroom/ 1 bath house that needs paint, carpet and light fixtures thats selling a little under market.

Flooring is old school tile, and 1 unit has carpet. 

Carpets, bedding and furnishings and anything that is worn out would need to go once you can get in.

If the kids have been painting murals on the carpet, that's another story.

Newly vacant after 5 year tenant destroyed nice carpet.

You can depreciate the building, furnaces and carpet.

Replaced all carpeting with high end flooring, fresh designer paint job (interior & exterior), updated all interior lighting, refinished kitchen cabinets, installed butcher top counters, added a custom "breakfast nook," replaced all windows, New HVAC & duct-work, cleaned up the overgrown yard and added exterior curb appeal, plus gutted & updated bathrooms.What was the outcome?