I honestly don't think Sink is a bad candidate. Her 2010 result was pretty strong, and it's not like she got blown out in the House election either (a non presidential year special election would've been tough for any Dem). Now, if Florida had a stronger bench, I'd still not want her to run for anything again. But since it's Florida, she might actually be one of our better candidates...
You're sugar coating it. Both of Sink's loses were an embarrassment. She shouldn't run again, Democrats should just put a fresh face out there.