Fair points. In answer to your question I feel sure that one may drink until sketchy also. I certainly wouldn't disagree that we're free with the employment of the word. It's become a catchall to deal with pretty much every context situation and emotion.
I can only advise that you try the word in anger while sketchy (or messed). It's beauty seems to be in it's usefulness - we have many converts.
PS. The 'sketchy incident in the toilet' could refer to anything: staggering about, talking to oneself, fainting, being ill, not really remembering how long you've been there etc.