The more time you spend on a tag, USUALLY the better the tag will be. Allthough, you can spend so much time on a tag and make something with great executoin, yet the concept and style may not be something people like, or which appeals to them. A tragic problem many artists have.
However with tag making, usually if you make a tag and you think its finished, spend half an hour neatening up bits of it (e.g. Colour failz, ragged c4d edges - fix with layer masks, blur and sharpen) spenidng half an hour doing this, or even 10 minutes will make the world of difference to your tags, being clean is a great asset your tags can have.