I agree on dumping something that isn't clicking.  I had a 126,000 word manuscript.  I had people read it and the overall feedback was positive.  But I noted the same negative comments and, more importantly, trusted my gut instinct.  I gutted the book, cutting 26,000 words, changing it from a thriller to a suspense novel (big difference between two genres).  I still have more rewriting to do on a character that just didn't work.  It took me a long time, but I never send something in to an agent or editor until I no longer have that tingling feeling in my gut telling me something isn't right.