Changing the gloves due to sweat and rips and nicks is a given, but they tend not to give up so quickly, with say tyre changing and brakes, from contamination I have found.
Being a cheapskate and tight sod I can make a pair last ages, airing them between uses.
On the subject of going to the toilet with them, I used to teach construction H&S at college and it was surprising how few lads washed their hands after going for a piss. I asked them to Google dermatitis and cement burns on damp skin and then asked them if they would now be washing their hands both before and after going. Hand washing improved drastically after that.
