Loads of people do this but it doesn't really work. It's not like the bass part is going to be completely contained with the frequencies controlled, especially the higher harmonics. It might work a bit with sub bass. At best mixing with the bass eq is a way of rescuing a clashing mix, although most times I've done it I could still hear the clash as there is still quite a lot of the eqd bass part there. I wouldn't ever try to use it deliberately to swap basses unless I'd worked it out first and was sure that the eq frequencies fell at the right spot. Can you imagine a producer sampling a track and "removing the bass" with a radical cut at a fixed frequency? If your DJ mixer has a swept frequency on the bass it might improve things a bit but I don't think I've aver seen that..? It always surprises me the number of people who leave both levels up full and reach straight for the bass eg to mix with. One of my mates was co-hosting my radio show with me the other day, happily driving the levels in to the red and distorting and when I pointed it out he said "but I've got the bass turned down"... A harshly eq'd tune layered at full volume over another tune is just going to sound harsh and loud, IMO using the levels carefully and then eq carefully to tweak any troublesome frequencies or compensate for the quality of the source material leads to a far smoother mix every time Dropping the bass on one tune does help if you find that you've got phasing issues between the kicks on the two tracks, but by the time the tune coming in is a full level you probably want to make sure the bass is full up (and maybe down on the other) cos it'll be affecting the sound of everything else (like the bassline and even the oomph of the snares)
