I've found that long URLs (whether it's a penalty or not, I don't know) have overall lower page rank than short, descriptive URLs. Another good reason to go with your /widgets/blue/fuzzy method is because Google will NEVER look at it as "Keyword Stuffing". The other method, if it isn't penalized now, might be some time down the road.
Even better, though, is to keep your pages up high and don't go too deep into a directory structure as PR goes down for each / in the URL. Your BEST solution would be:
/widgets/blue_fuzzy.html
/widgets/red_fuzzy.html
/widgets/blue_smooth.html
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