Gee, I'm sorry, Rio, I didn't realize that woman was YOUR ladyfriend.
Seriously, I think MrLV may be on to something. Sure, it could be a fellow monger with some warped idea of how to show off his knowledge. If so, I'd be curious to know how he explained his OWN visits to CR and whether he 'fessed up to what HE'S been doing or else pretended like he was "above" all that (like most of us often do when faced with those sorts of suspicions). Still, I think the repressed judgmental moralistic missionary seems a more likely explanation.
I also agree with Rascal that CR sex tourism is not great secret. Most US mongers know about it, whether they've been there or not, just because they normally travel in circles of like-minded guys who know all about it. However, that doesn't mean that the average person who doesn't know much about CR is particularly familiar. For them, the first words of association are more likely eco-tourism, bananas and coffee and, if you mention sex-tourism, they might say, "oh yeah, I seem to recall hearing something about that too".
Even if they've heard more about it than that from some evening news special, they still may not be fully aware of how extensive it actually is. After all, they're much more likely to know people who have been to CR for all the OTHER reasons - eco-tourism, surfing, fishing, missionary work etc. - and very few if any who would admit to them that they're one of those disgusting mongering guys. We think mongering is a bigger part of CR tourism than it is because we spend most of our time in the Gulch (or Jaco) where most of the mongering is concentrated. But most tourists who come to CR avoid SJ like the plague and mostly see just other tourists like themselves at places like MA, Arenal and Monteverde. Based THEIR perspective of CR, why wouldn't they be able to believe or at least allow themselves to be easily fooled that you're part of the "normal" tourist groups? Sure they may strongly suspect about the real reasons you keep going to CR, but there is a HUGE difference between that and removing all doubt.
Maybe, instead of using fishing or gambling for our cover, we should take a cue from these missionary types and find some volunteer work that can be done in a few hours each day somewhere in the SJ area. That would still leave our nights and maybe afternoons free for other activities AND it would be a lot harder for these morality cops to question or find fault with what we say we are doing in CR. Sure there are flaws even with that approach, but it may be a worthwhile idea.