When refurb'ing the bathroom of my flat that had been occupied by
between one and two males for the last 13 years I couldn't beleive
what I found. When I lifted the toilet base it was as though somebody
had lit a small circular bonfire on the floor. Admittedly, part of it
was the bodge job done by the lino installers, I'd specified that it
go /under/ all the fittings, instead they "carefully" trimmed it
around the bases. I had to strip all the flooring out and replace it.
Luckily, it was cladding used to give a smooth surface, so I could
just reclad it. I still had to spend several hours on my knees with
bleach and a scrubbing brush sterilising the underfloor.

So, ensure lino goes /under/ the loo, and use a supply of fluffy
toilet cosies and chuck 'em away at regular intervals.

JGH