I haven't opened it in a Hex editor yet to see what tags they are using but on initial view they are using ID3v1 and v2 tags. Here is the info on the track I downloaded:

Artist A Perfect Circle
Title 3 Libras [Explicit]
Album Mer De Noms [Explicit]
Track 6/12
Disc 1/1
Genre Alternative Rock
Year 2000
Rating
Composer
Size 6.64 MB (17% of original, 1 to 1 compression)
Original Size 36.95 MB
Length 3 minutes 39 seconds
Channels 2 (stereo)
Sample Rate 44.1 KHz;
Sample Size 16 bit
Bit Rate 253 kbps
Encoder LAME 3.97
Encoder Settings Variable Bit Rate -V 0 (Extreme)
Audio Quality Very High (Lossy)
Contains Album Art, ID Tag [ID3v2.3 (ANSI) & ID3v1.1]
Channel Mapping Left, Right
File 06 - 3 Libras [Explicit]
Type Winamp media file [.mp3]

Everything looks good to me and shows up correctly in Winamp, iTunes, WMP 11 and my Sonos system.

If you are altering the data and not seeing the changes, my guess would be you're altering one of the ID3 tags and the reader is reading the other tag. I know how to remove ID3v1 tags in Winamp and iTunes, but not in other programs (I'm sure Google can save the day).

-Jason