You're right, if you boost the EQs on your mix and the listener has their set up boosted, the sound will be over EQd.
I usually keep the EQs flat on my DJ mixes and I don't do any additional processing either. After all, the tracks I'm mixing together have already been mastered once, so why should I try to master them again? If there are problems with levels and blends in your mix, then you need to work on your mixing rather than trying to cover it up afterwards.
Just my 2 cents
Distortion is evil