There are times when it can be useful to self-deprecate. Particularly when one is socially dominant, self-deprecation can help put others, especially introverts, unattractive women and lower-ranking men, at their ease with you. Sitting in silence can be uncomfortable and unpleasant, especially at a social event, and often those less socially skilled (or less socially desirable), individuals can be every bit as intelligent and interesting as their more superficially attractive colleagues.
However, self-deprecation is also dangerous, particularly for deltas and gammas, because it should NEVER be used as a way of attempting to gain either approval or sympathy, much less to generate attraction. While I am aware that Wounded Bird Game is a time-honored seduction tactic, it does not generate attraction, but relies upon the attraction already being present. To attempt to use it in order to generate attraction is a category error.
So, self-deprecation should only be used when you are dealing with people who appear to be uneasy or overwhelmed. Humorous self-deprecation is best, such as an incident when you behaved poorly, something unexpected happened, and you ended up looking ridiculous as a result.
For example, I was at an event where those around me had pretty much exhausted all the obvious topics that occurred to them within ten minutes. All very smart people, all international, but not exactly prom queens and football captains. So I told a story about Americans blundering abroad, which culminated in four very hungover college students urinating in the only patch of green they could find in Tokyo, only to discover, in mid-stream, that they were relieving themselves right next to a little old Japanese lady kneeling down and wearing a giant straw hat as she worked in her tiny garden. It was the worst American behavior since Vietnam!
The ice being completely broken, everyone laughed hard, but the real punchline followed when I told the guy sitting next to me, as if on an unrelated tangent, "You know, I've always wanted to visit (his country)".
He pretended to look horrified, of course, and said, "Please don't", which cracked everyone up again. After that we were all on a socially level playing field and the conversation flowed considerably more naturally.
So, there is a place for self-deprecation, but use it in order to make others more comfortable, not as a passive-aggressive way to make yourself look better, which it really doesn't do anyhow.