No, I've never had sex in a public bathroom. I have always valued sex too much to do it where others shit and piss. I've always been disappointed in other gay men when I've walked into a restroom and sex between men is going on--I leave quickly and find another bathroom. Wouldn't want to be in a place like that when a vice arrest goes down. I have know instances where some 'watchers' have been arrested (for loitering) along with the participants. Just think of US Senator Larry Craig (R-ID) arrested by a vice cop in a bathroom in the Minneapolis Airport; his veiled threat to the arresting officer ('Do you know who I am?') didn't keep him from arrest, public humiliation, and having to leave the senate in disgrace.
I know men who
1.) have had careers damaged or cut short by arrests for restroom sex/public lewdness/indecency;
2.) have been passed over for jobs or lost a security clearance or have been dishonorably discharged because of a public indecency arrest;
3.) have had to live with the embarrassment for having been arrested for, sorry, being a toilet fuck.
Having sex in a bathroom that has dirty floors, dirty toilets (because they ARE toilets), and that smell bad because of effluvia or restroom deodorants, where sinks and faucets are disease-transmission vectors (fomites) has never appealed to me. I hate entering a stall with either cum on the floor/toilet seat, orcum tracks on stall walls--it's like an animal leaving its spoor. I just walk away without using that stall.
Hot gay sex is so great that it deserves a good setting with privacy, and for me, that's not a public shitter.
It's certainly not the case, as it used to be, that such places are the only place that casual gay sex can occur.
I'm not a prude, and yes, I know that for some filth is a fetish, just not for me.
Don't bother to attack me, this is just my own experience that the OP asked for, along with my personal opinion.