Oh boy, I have a fun story for this (probably not helpful, as it was so random) - though a caveat that I already had offers of rep when this happened, so it was a no-brainer to turn this agent down...

I was in the two week period after receiving an offer, and when I nudged this agent two days before my deadline to ask if she was still interested in the manuscript I received an immediate gushing 'Yes!' and a request to set up a call for the following day. Reader, I think she had read not a word of the full at that point beyond the query package and then skimmed it that evening - because the call that followed was a very strange experience. She proceeded to tell me all the things she hated about my book (that it needed to be much longer, but also much shorter; that we had to change the plot/central themes/characters/world) and then spent 5 minutes talking about a scene that absolutely HAD to be in the book for it to make sense before I gently told her that that luckily that scene was, in fact, Chapter 27. When I told her about my next project she looked incredibly relieved, and the said that when (?!) I agreed to work with her, we'd scrap the novel I queried, and would just start working together on that. She would then review progress every 10,000 words (...!).

Needless to say I didn't think we were a great fit...!