I'm quite unlucky on this score so I am double extra careful now i.e. only b2b and HE. Even then have had some scares i.e. unrequested OWO during the b2b.
I contracted a very nasty STI from, again, unrequested OWO (I thought she was putting condom on but no, I became her 10th or 11th cock of the day in her Spanish mouth). Bright red wound-like thing on the edge of my bell-end, swollen balls etc. Was shacked up with my ex at the time and had to invent excuses to not do it for weeks until clear. The same ex I contracted some kind of STI and didn't even know I had it and gave it to her, fortunately the symptoms in her could have had multiple causes but when I got tested there it was. Again, when young and stupid I occasionally even did it with my ex (probably why she left me) hours after doing a WG.
I have occasional sex with a woman I met in a shop (who no longer works there) but this is more a FB arrangement than paid (she asked me to stop offering her money whenever I went round LOL). She seems very on top of stuff (usually me) and as worried for her own hygeine as mine.
Quite enjoy unprotected sex with my OH so I'd not do anything to endanger that, touch wood. The only downside of it is not having enough in the tank all the time for HE sessions.