conuly

Regular cleaning is not that effective, even supposedly thorough cleaning is not that effective (http://www.sciencedaily.com/releases/2008/05/080511094422.htm). Sure enough, most of the time, toilets are harmless enough, but the chance of coming across a harmful bacterium there is higher than in a number of other places, including ice machines. Lax cleaning of either ice machines or toilets may however present a harmful concentration of otherwise benign microbial life.

Also, even though urine itself may not harbour much life, skin does, and on women's toilets skin touches many a place, and the urine itself picks up some life in it's passing. There is also fair nutrition in urine and faeces, and life may thrive in the portion that is not flushed.

All said, healthy respect for, not irrational fear of, human waste is advisable.