Here's the problem tenant mattress had some water stains on there from the toilet leak.

I was able to get carpets professionally cleaned which got up roughly 90% of the stains. 

But to be fair rentals are the smallest portion of anything we do.Where things like sealing and staining are concerned, a homeowner and products from box stores have no place and likely their knowledge is less than stellar when it comes to chemical compounds and one kind of acrylic vs another etc.

I'm in Cleveland area, my guy I've used for the past 12 years.....full refinish (sand to apply choice of stain + 3 coats) $3/sq ft., sand and three coats no stain, $2.50, dress with light sand and topcoat and buff $1.25. 

A lot of people may look around a room and say, "oh, it looks fine as it is," as they stare at wallpaper from the 70s and stained, green shag carpet LOL.Your best bet is to go as low as you can in price.

One of our couches has large sticky stains that were not there before.

For example, a wood platform would require staining and board repairs over time.

does the ceiling look like its had recently been painted or water stains around the edges? 

Broken doors, counter cuts and damaged, mold at windows, carpet stained in multiple locations, painting without permission. 

Since I did the work myself, the costs were only $2k for all the stain and sander rental.