Everybody speaks in a certain dialect/accent/register of a language which should be recognizable to the informed outsider. The homeless person getting the point that you were Californian is a good example of this - in the United Kingdom there is quite a lot of television exposure to various Californian accental varieties through a number of sitcoms and other shows, so for the one with a good ear it's quite recognizable.

What I find interesting though is the point that you've never really thought of yourself as speaking in a certain way. I mean, personally I found that just hearing people speak differently all the time made me automatically conscious from early on that I must talk in a certain way and that it is only one way among many. It's interesting to try to put on other regional accents and then to carefully observe and consider the huge amounts of differences in pronunciation, intonation and so forth; tests like this make one realize just how much they themselves are speaking differently.

Yeah, it's fun trying to pick out different accents. Regional variation is more prevalent in some places - for instance, I've heard that if you travel in a 20 km circle around Manchester, you'll encounter some fairly distinct accents.

Even in NZ, there is a degree of variation... if you've ever seen Eagle vs Shark (NZ's Napoleon Dynamite featuring Jemaine from Flight of the Conchords), then you'll know what Lily's accent sounds like... here's an example. There are many NZers who would find her thick accent cringe-worthy - that's an example right there of regional variation.

I always thought Californian was rather neutral.

Some of the nicest people I've ever met are from the southern US, lol, being from way up north I guess we talk a lot faster than our deep southern neighbors and they always know instantly that you are a foreigner. I really enjoy the languid laid back dialect from Texas, Florida etc...it's just so different from how we talk that it makes the simplest conversations more entertaining. When I travel down east to Toronto for instance, my relatives have almost a Tennessee accent compared to out west, some words in particular stand out instantly. I do speak a little French on occasion and I enjoy many European accents as well, the diversity of people from different cultures is what makes the world such a great place.(And even within our own countries as many of you have already mentioned.)

It has everything to do with your accent.

I'm amazed you know that!
I think British Pharaoh lives in the Ashton area of Manchester which is only about 3 to 4 miles east of where I live and the accents are noticeably different.
I've heard Molecules or was it Guitar Bizarre??? talk on a youtube vid and I'd guess his accent is south to southwest of the city centre somewhere.
Probably only a few miles from where I am, but again a different accent.
Pheurton who lives over the hills further east probably speaks with a hair lip due to centuries of inbreeding.

Yheesh, so close together. It's a wonder you're not all inbred.

I hated this first time I heard it but it is pretty good I have to say:

Yeah, I was under the impression that western/midwestern accents were as neutral as standard American English got? Which is why I've never really thought of myself as having a regional accent.

That was awesome...

Yeah, I think I have a similar situation in Croatia, I live in a town which I've always considered speaks pretty much standard Croatian, but everyone else says that you can easily tell that someone is from there. I figure it's because when everyone else speaks with some regional peculiarity the standard starts to stick out. Apart from "dude" I haven't really noticed anything that would scream California...:|