It's easy if you're the one putting forward the task for which mastery of X is needed: (1) add clear bad consequences for failure; make it sure that the job is

It's easy if you're the one putting forward the task for which mastery of X is needed: (1) add clear bad consequences for failure; make it sure that the job is "so easy" for "someone master at X"; make it obvious that failing can only occur through their fault; add that "this is a crucial task" and its bad execution could threaten the future of all; hint at ways of future public shaming in case of failure, preferably in a humorous way :), (2) add an expected performance quotation "someone knowing X should be able to do it in N days easily" and (3) add some VERY desirable reward for task completion, that includes social status increases, but it's also conditioned on a performance metric like time/budget spent, not just 'task completion'". The above will discourage anyone faking competence. The high reward that includes peer recognition will attract the truly competent ones. Also it may help if you try to understand the problem better. Try and figure out what are the motives of the persons over-selling themselves. There are on one side desperate extroverts who really need/want a job/project that requires them to have mastery of X, or they really want the client for whose projects mastery of X is required. So they play the "fake it till you make it". Of course, this is the optimistic perspective, some "just fake it", some become blocked in ever making it because they've faked it. I'm an introvert but I've played this game once myself - never again! (The insane amount of work that I had to do while also learning something I claimed to know, in a "jump straight in" way that slowed my learning paradoxically because I did not have the time to sit and learn the fundamentals was horrible and nerve wrecking.) -- There's noting to do about these people than avoid them, they'll learn their lesson and move on! Then there are the "chronic deceivers". They cannot be dishonest in one aspect alone. -- So to deal with them just prove to the _others_ that they are untrustworthy. You can toy them into saying contradictory things if you're clever and have the time to waste. Or maybe ask them for help on something in front of other people in a way that if they say "no" they are either _assholes_ or they don't really have knowledge of X - both outcomes help. Then the ones that also falsely believe themselves to have mastery of something. -- Just make it obvious to others that they are clueless and stupid in general.