Personally I would refinish floors instead of tile and I wouldnt do it because I dislike height transitions so I would tear out the hardwood in kitchen so tile and other flooring was flush.  

But, this constant complaining (closet smells, the refrigerator shelves are dirty, the cabinet knobs need polishing, whoops I flushed a towel down the toilet- come over and snake it for me) is getting sickening.

I had one horror story where a guest's kid flushed a fake plant down the toilet and it resulted in a $4,000 sewer line repair.

@Gregory Schwartz purely my opinion....I think all this pandemic is going to do is to flush out anyone who was half assing it, anyone who didn't do their homework, and people who got emotional. 

But I also assume the out-of-state money is flushing more local flippers into your areas.I think the main issue is the regulation against building more housing. 

Didn't realize this until after the tenant moved in and texted "tubs not draining, toilets, not flushing, sinks aren't draining"...

Just treating the bad unit will flush the nasties to safe harbor in the units that have not been treated and then you will have your good tenants mad at you.Since those nasty tenants have already done their damage but are still willing to live there...you might as well collect as much rent as you can before you decide to force them out.  

For example,I install the standard ball valves underneath every fixture/sink, use TOTO Drake toilets (strongest basic flush system ever!!

Many of our landlord clients have clauses that make the tenant responsible for drain backups if they flush something down the drains that shouldn’t be flushed.

You turn off the water, pull the tower off the wall, unscrew the leads, flush the system, connect the new tower, and hang it back on the same brackets.