Quick like, and lest you think I am going to use this blog to constructively criticize other people's webcomics, I'll link you to the recent failed incarnation of my own webcomic, Upstate!. I started the run in late 2006 and it lasted a year of spotty updates, to about 80 comics. I really have come a long way since then, to the point where my old comics here make me flinch. It's certainly not required reading, but it's a treasure trove of many common mistakes and general failure. I prefer to use them before I use someone else's webcomic as examples, where possible.
The earlier run of Upstate!, which also updated poorly from 2002 up until 2004 (when I was activated and sent to Iraq for a year) will be uploaded somewhere at some point, and also used as fail-fodder. I can honestly say that the Upstate! I am working on currently is a completely different animal than my first two tries, although they share characters. It's not something I am ashamed to share, if it helps people out.