Probably are junk. If VLC cannot play them then I'd doubt any player could. Check the file sizes in my previous link, try to get to learn them off by heart, you will after a while. Also keep this in mind: mp3 Bit-Rates Versus File Sizes (click on link). This bit rate technique however takes much looking & comparing to be sure you see the file size, bitrate & length of song to compare them. This might help too: How to find music which also applies to video searching.

If music files do not show bit rate in search results then probably junk. Also if you see something silly in the title like file-name followed by 320 kbps then you know it's most likely junk. Junk generally has less mp3 id3 tag information than real mp3 files.