While bathing, the mosaic is gone.and it actually took me a few years to realize that. It appears before they get in the shower/tub and as they are exiting the shower/tub.
In TS1, for instance, they have a form-fitting (like a bath-towel) sized mosaic. I have never used a mosaic removal mod, but I can't help noticing how much more obtrusive and blocky the mosaics become with each new addition to the Sims line. My husband really wants me to install it, but I couldn't even keep no mosaic installed.