If you haven't yet, it's pretty interesting to check out people's answers to Friday's question, where I asked: If you were to play a game set in the DC comics universe, how quickly would you figure out that Clark Kent is Superman?
When I initially asked the question, I was just thinking of it as a simple example of how to apply narrative logic to play (not recognizing them is, in most circumstances, narrative appropriate) without needing to stress yourself out. However, the answers I've gotten to this question have really suggested to me that this may be an incredibly informative question to ask at the beginning of a campaign. It's a question with no wrong answer, but each right answer reveals a very different relationship with the fiction of the game.
Some of the big groupings I saw break down like this.
For some people (including myself), the answer is "never" (with minor qualifications, such as if he reveals himself). This is full trope buy in - treating the narrative logic of the setting as something as concrete as the logic of physics.
There were also several "Never, except..." answers that broke into two categories, tropes and stories. For the first, they would see through it if it was their particular trope (that is, if they were Batman). I tend to consider this the same as the first group, just elaborating on their position. The second group was a bit more varied, but in general they would not notice unless their personal story took thing sin that direction. As a category it's maddeningly fuzzy, but I seperate it out from the tropers because while it's also narrative logic, it's narrative logic based on a different priority stack. That is to say, it prioritizes the personal story over the setting story.
Some people nitpicked the question. You might think this does not reveal much about their play, but then you'd probably realize that yes, it probably does.
Another group viewed things through a very practical lens, and felt it really just depended on how much time and exposure they had, but given both, they would work it out because it's just logical. These pragmatists are more or less the opposite pole from the tropers, and aren't invested in the narrative logic of things.
Now, these groups were all more or less what I expected to hear from, but there were two other groups that surprised me as common responses, not just odd one-offs.
The first are the "immediately, unless..." crowd. At first blush they seem like the pragmatists, but they actually are totally willing to be "nevers" if they can can given an excuse, however thin. Super hynotism, superspeed, kryptonian muscle control or even really good acting - as long as some sort of explanation is in place, they're willing to suspend disbelief and buy into it. That is to say, they're willing to buy into comic book logic more than any abstract about narrative.
The second are what I consider "Immediately, because...". For them it's not about the logic, it's that breaking the premise is a desirable outcome. They are using the setting specifically so they can move things around, shake them up, and even break things.
Now, I'm not going to bother with naming these groups in any systematic way - that would be kind of silly, but I want to highlight a thing or two. See, a lot of people were surprised at how others answered, and it seems like the kind of surprise you don't want to have happen at your table. I can absolutely think of problems that have emerged in games I play that were a result of a single "Immediately, because..." player, not because that player was bad or problematic, but because his expectation differed so much from the rest of the table.
This is why I think it's a great question to ask before a campaign, but I think it's a question to re-ask, perhaps tuned to your specific campaign, every time you start something new. See, there's an inclination to think that these are player types, but that's just not the case. Some players might always pick the same things, but others will change choices dramatically as you move from genre to genre. Supers, for example, already calls for a certain level of suspension of disbelief from its enthusiastic fans, and someone who might willingly buy that glasses conceal Superman's true identity would NEVER tolerate that kind of "Disguise" in their urban horror or sword & Sorcery game.
Anyway, it's a question I encourage you to ask your players. Feel free to refine it as you see fit, but Clark Kent's glasses are a sufficiently universal symbol that there aren't many people who won't "get" the question as asked (so long as they "get" playing an RPG).