I find that cleaning used records very difficult

Hi
I buy many used records from thrift shops and used Records Stores. I ussually play them 1st if they are decent. I'm finding out that many times that eaven thought the records looks like it needs cleaning. I play it and it actually has the true Vinyl sound ( Thats great but it looks dirty)and as soon as I wash it with my $500.00 record machine and distilled water, it seemes to lose that deep bass on guitar or other instruments.
Its like it leaves a layer of something that takes away the highs and lows.
.
I even had a few records cleaned on much more Expensive machines like $4,000.00 machine and it also seems to do the same thing.

Has anyone one else experienced this and does anyone have a better way of cleaning records.