Recording to Cassette 'muddies' the sound?

Hi, all.

Just got into cassette and am loving making mixtapes, but I find the playback is always super bassy/muddy compared to pre recorded cassettes? I bought a set of maxwell tapes off amazon and they are so bassy I can hardly listen to them.

I also bought a set of randoms from Duplication.ca and they are much better but still really bassy.

What can I do? I've cleaned the play/record heads and have adjusted azimuths accordingly already.