Woody... Welcome to the dark side! The fear of STDs is always there. You take as many precautions as you like to reduce risk, but nothing is fool proof. If you are overly concerned, you will never completely enjoy the hobby. If that's the case, settle down in a nice monogamous relationship.
As for whether guys would 'fess up on here... I had a scare recently which involved either a well known SP in KW or a well known SP in Toronto. They were the only two women I had seen during that time. In both cases, I let them know that there was "possibly" an issue, and that I would advise them once my tests came back. I was pleased when both responded very professionally, indicating that they had both been recently tested (4 and 6 weeks respectively as I recall, although we all know a test is only as good as the last customer...) but that they would immediately get tested again. They did not stop working, or take additional precautions as far as I know. Both were the so-called "Classic GFE"...
As it turns out, my scare was just that. I was negative, and I advised both women of that. While I was obviously happy with the result, it did give me pause to reflect... and led to a temporary break. While I was waiting for the results, I considered whether I would post on here, naming names, but concluded that considering the number of women I had seen, and that these infections could possibly be dormant for some time before becoming symptomatic, it would have been impossible for me to say without doubt that I caught something from from one of these two. Even if it was one of them, there would have been no way to confirm which, so I had accepted that I would probably just need to let it be. I thought I would post a "generic" warning... although that wouldn't have done much good I suspect.
As is usually suggested whenever this topic comes up, I rationalized about getting hit by a car etc. You will need to decide if the rewards justify the risks. I suppose this is different with everyone, and it will vary depending on your marital status and a host of other things.
Before anyone asks who the two in question were, I won't tell you since it is no longer relevent.
On that happy note... enjoy!