actually the only time i have edited a mix was when my needle jumped . yeah my records are under the table on which my turntables are and after having found the next record i wanted to play i hit my head on the table while standing up again :P
now everybody can say i am a big cheatter and that one of the most essential dj skills is to take care of your head :D
more seriously i always leave the trainwrecks wheni reord amixthat just a matter of being true... if you are a sucker and that your trainwrecks are so big that you feel obbliged to edit them then that means you have to give djing 8)