I think of enzymes primarily in terms of carpet and porous surface cleaning and as mitigating odor, both in porous items and in drains.
Here’s an article that describes how to use them as odor control and cleaning agents on hard surfaces in bathrooms.
I’m still of the opinion that physically removing soil from non porous surfaces is pretty close to 100% of the solution, but a couple of observations:
– Grout is porous and irregular – hence hard to remove 100% of odor causing soil, hence enzymes are part of the solution.
– Even on a hard non porous surface like porcelain, there can be pits and irregularities that trap soil, hence, again, enzymes left behind from a cleanser would help.
The same caveats with all applications of enzymes apply – you need to leave enough moisture on the surface for the enzymes to activate and “dwell” long enough to do their work. The article sidesteps this a little bit with it’s recommendation of repeated use.
– You’re going to do better with a neutral surface – if you are putting acids (or alkaline all purpose cleaners) on the fixtures you might want a clear rinse or two to get rid of any residual ph.