Right now it seems genres are not being reset when scanning again. you
can just reset the database
http://code.google.com/p/streeme/wiki/InstallingStreeme#Initializing_your_Music_Library
and do another scan until the bug is fixed for good. Another thing is
that there are a number of preloaded genre tags to support old ID3V1
tags that aren't necessarily used - in id3v1, the genre is a number
not a text label. The relationship between song and genre is made at
scan time.
-Rich