Ok about contests...I think they're great, but me being wonderfully smart and usually submitting my works after hours of lack of sleep, I tend to forget to compress my thumbs or they're two pixels too large or some weird thing like that.  So naturally, my contest  entries are entered sans requiered thumbnail.  

My point:
Could there be some sort of "your thumbnail was improperly sized, so your entry was not submitted" instead of "your thumbnail was improperly sized, but your work was submitted anyway" type deal?