I began to arrange my MP3 collection by albums, and couldn't find the album that "Every Rose Has Its Thorn" is in, so I googled a little and found out many many people who did the same mistake as I did.
I don't know what's the origin of this massive mistake, but you should be careful when tagging your MP3!!
Some more exapmles of tag mistakes I had (most of them were corrected in the first month after I aquired the file):
* Man on the Silver Mountain mistakenly tagged as song of Dio
* Lady in Red mistakenly tagged as song of Roy Orbison
* F.B.I., mistakenly tagged as song of Queen (not that wrong, though).
* very old one but still be carefull -
Brain Damage was tagged as "Lunatic" (this is a very COMMON mistake made by non-PF fans)