Well, Cryptocat is open source, for starters. Also they state the risks pretty plainly:
Cryptocat is not a magic bullet. Even though Cryptocat provides useful encryption, you should never trust any piece of software with your life, and Cryptocat is no exception.
Cryptocat does not anonymize you: While your communications are encrypted, your identity can still be traced since Cryptocat does not mask your IP address. For anonymization, we highly recommend using Tor.
Cryptocat does not protect against key loggers: Your messages are encrypted as they go through the wire, but that doesn't mean that your keyboard is necessarily safe. Cryptocat does not protect against hardware or software key loggers which might be snooping on your keyboard strokes and sending them to an undesired third party.
Cryptocat does not protect against untrustworthy people: Parties you're conversing with may still leak your messages without your knowledge. Cryptocat aims to make sure that only the parties you're talking to get your messages, but that doesn't mean these parties are necessarily trustworthy.
Confide, however... all we've got is their word:
How secure is this and do messages really disappear?
We employ end-to-end encryption to ensure conversations remain confidential and are private to you. Even we at Confide cannot decrypt or see any messages. Yes, after messages are read once they disappear.
And yes, the founder of Bitcoin got into some hot water over soliciting "murder for hire" on the deep web. Source.
Both of these are more likely safer than, say, this community for example. If the feds came after Luna for information on one of us, chances are they would end up getting it. No offense, Luna - I'd turn over someone in here rather than risk my own hide, too. ;)
I'm also not advocating any of us start using this instead of this site. I was just throwing out some useful information to fellow paranoid people - nothing more. It could be useful for, say, these "raids" we are plotting. Discuss the details under pseudonyms in Cryptocat, then go do it. Or just use the apps to cheat on your wife. Hell, I don't care. I just like sharing information. :P