1) Link to the thing of ugliness you have found. If you like, you may also include a photo. But this must be in addition to a link.
2) Snark the fuck out of the thing. All posts should contain your commentary. If you're not witty enough to do the thing justice, don't bother.
3) Do not delete your comments, other people's comments, or your posts. Ever. Do not screen or freeze comments. Doing any of this will get you banned on the first offense, just like in
stupid_free.
Edits and Clarifications:
The ugly crap can come from any source - eBay, a web store, LJ, etsy, etc. If it's a product, and it's ugly as sin, it's game.
If snarking an eBay listing, it may be a good idea to screencap or host a photo of the ugly, since eBay listings disappear after 90 days.