"NO sign" is an opposition to star, it is a comment left in metadata for this file by user, this is a kind of warning against bad file naming (content is different than naming) or bad quality or anything else wrong with this particular file, just fake. Unfortunately some as.....s use it to left comment "download super-hiper-uper-emule now" so this is not 100% sure or accurate, like users comments. You should be able with 2.4.0.4 debug build to see comment text in search when source is compatible, however I am not sure. Stars indicate OK, more stars more OK, "NO sign" just is a warning an is only one. You can leave your own comments and rating, just by rating files in Library. When you will see how it works you will have no doubts I suppose.
btw.
Download (G2) and read "Shareaza Install Guide" - IMHO now best Shareaza tutor.
And read Shareaza wiki, however devastated and not fully recovered yet, but the largest source of trusted knowledge about Shareaza still, and under continuous updating by users.
If you like Shareaza you owe community: in return let to know 2 or 3 of your friends about Shareaza and why you like it. This is usual and informal "entering community tax"