In general it's like Vera and waddlerafter said. Disguises and ambpop MEAN something and players need to respect it even if it means that their characters have to hit a dead end. Get over it. Sometimes the other guy gets away with it and there is nothing you can do. Please top being meta and small worlding.
At the same time, Ranger and Grizzly are right. people ARE going to do this. It's not even that they mean to be malicious. Sometimes they don't realize what they are doing. Sometimes it's in the heat of the moment and they are typing faster than they are thinking. So take extra measures. Make sure you put in the extra touches that will make IDing you even harder.
Lastly, please do not take 'gut feeling' and 'my character is just that reckless and impulsive' too far. The fact is that if you applied these things in a real city of 70 million people you will be wrong far more often than you can be in Sindome given player density. And the impact on you for being wrong will be far less. Though we can start doing something about the latter. Maybe start killing informants that give you wrong or weak paydata. Go for it!
If you want to use 'but my character is impulsive and assumes things' as an excuse to ID people when that ID makes no sense, then I want to actually see you get it wrong too. Even id you the Player has to make it happen. If all I see is a string of meta guesses that were right and the constant excuse that 'my character is impulsive and assumes things,' I'm sorry I'm calling that meta.
In general I urge you all to ask two things. Seriously slow down and ask these questions. Think about them. Imagine a GM like myself asking you these questions and picking at your answers.
Do I have solid reasons to believe X?
Are there reasons why X might NOT be true?
You need a Yes/No result here before you should be acting like you know. The fact of the matter is that many people feel that their reasons are far more solid than they really are and that most do not even ask themselves that second question. That second question will often demonstrate that what you felt was 'solid reason' was actually a boat full of so many holes it's sitting on the bottom of the ocean and you're drowning. :-P