Unfortunately I have as well. Back a few years ago, when I was a "safe" hobbyist only doing sensual massages.
I saw a lady, smoking hot I might add, she did a respectable body rub. More of a rub and tug to be honest. She got a little carried away and dug her nails into my upper thighs. It was pretty hot I must say, but a week or so later I noticed what looked like a pimple on my upper thigh. No big deal, had them before. Well, the pimple, white headed thing, got bigger. Now I thought it was probably an insect or spider bite or something. I'm outdoor up north a lot. Plus, now there were 2 of them, another small one started. Quite red around the area as well.
Still didn't panic, or connect the massage with this. The pimples kept getting bigger, much more red, and turning into more of a lump. The bigger one was starting to weep a little clear fluid. Now I'm getting concerned. Went in to the doc. It was too long ago nowfor me to remember what he thought it was, but he gave me some meds.
He took a culture just to check, and called me in a few days, told me to stop taking the meds, it's MRSA, Methicillin-resistant Staphylococcus aureus. Told me to come in to get some antibiotics. First antibiotic didn't work, second didn't, finally the third one did.
On vacation a month later it came back, but was able to knock it out right away.
Scary. Never heard of MRSA before, basically a staph infection. Most likely places to pick it up, hospitals and prisons. The link describes it a little. Explained to the wife probably picked it up in a hot tub.
So much for playing safe. The massage lady probably had fecal matter under her nails or something, only thing I can think of.
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004520/
Posted By: creativefunguy
unfortunately yes, years ago, she got hot wanted it bad, no condom, she gave
me chlamydia
went to the doc, got a pill, all better
BUT it could have been much worse, I lucked out
rule of thumb, No glove, no love
peace
I'm a s3xual ANIMAL! 
lol