It's sometimes hard to explain how I can tell the difference between false bravado and real bravado. Well, maybe not. Most of the people with false bravado don't have the science on their side. Thanks be to statistical mathematics for being able to explicitly quantify confidence.
Creationists always come across as the most desperate to me. Unfortunately, most don't even understand the issue, so they think their random theory of randomness actually has an edge over the reliability of evolution. If they weren't so wantonly repetitive it'd be merely sad instead of frustrating.
I suspect many anti-vaxxers are aware how poor their position is, since they have to change hypotheses every couple of weeks. They were certain it was thimerosal over here, and now I'm hearing it's Children's Tylenol + vaccines, the third most common element in the Earth's crust (after oxygen and silicon), a handful of antigens out of a child's daily dose of thousands "overloading" the system, and some weird Yin and Yang crap I rolled my eyes past that I think Happeh said a while back. They can't be all that confident if they have to change stories on a continuous basis.
Homeopaths are generally clueless in my experience. They aren't even aware of what we're complaining about: Coming up with new magical mechanisms doesn't help if you don't have a cure to explain.
Most conspiracy nuts I know seem to have a bit of double-think: They're absolutely confident in their theories, but when confronted with a skeptic, they usually have to flail around and change topics.
So, experiences to share?