When the house failed because the tenants failed to clean the bathtub of mildew (and he listed it as the dreaded "mold") and the drip pans under the range needed to be replaced, guess who had to do this. 

My tenants go for "clean" not "fancy"  The other bathtub in the house has only slight discoloration, and is a soaker (bigger) tub.  

There is a bad clog in the bathtub and you have to hire a plumber. 

@James Ross depends how big the house is/how many people would be living thereTankless last longer and has a longer warranty but also needs more routine maintenance(once a year) which cost I believe around 200$ unless you do it yourself.But nothing like having a bathtub that actually fills up hot all the way!

Many times the whole drain assembly under the bath tub has failed/leaks. 

However, having a toilet just a foot from the bathtub in the guest bathroom is a big turnoff.

@Graham NadlerVinyl floor, no garbage disposals, a paint color that can be used as "touch up" (i.e. without having to repaint the entire wall), pex pipe, a working fan in the bathroom, leave a few furnace filters behind for either yourself or the tenant to change, no screens unless lease says tenant will maintain repairs, bathtub surrounds that use very little to no caulk (reduces mold).

The potential home has a bad master bath tub so we were going to rip out the tub and do a big walk-in shower.

The bathrooms get a full tile replacement or combination of a new bathtub with a new toilet and vanities.

Sometimes, the city nails us for lead testing in ceramic tile walls, floors and bathtubs.