They are the only types I haven't come across (At least I think)
I suspect that my stepdad may be an ISTJ but and my co-worker and ISFP but I'm not sure.
Most of the others types I feel I can pick out froma crowd but I don't really have a sense of the ISxxs.
You would have a hard time finding me in public. I tend to spent most of my time outside of home at work or doing specific tasks like going to pick up a book or whatever it is that I might need to do... (Not much)
Oh, I'm never CERTAIN about people's types, I'm really not. I don't think I'm that good at typing people. But some indicators I'd say:
-Long attachment to a few close friends
-Fine with their own company, though they still "need people"
-Passionate about certain long-held hobbies and enthusiasms, with a very fine recall for details about years, places, people, etc.
-They lose me when they start talking about their apartment renovations and their new laundry machine. I lose them when I start talking about my new poetic insight. But we still get on great and have similar interests, despite somewhat different ways of coming at things.
In general I'd get ISxx from the above, though I'm not saying it's conclusive.
You'll find a lot of ISFPs in some local music venue, I bet. I know two ISFPs off the top of my head in their mid-to-late 20's trying to pursue their music dream. They may be the easiest to find in that they can be pretty passionate about their interests and desire to express themselves in that area. They also can be pretty sociable, and may not be as aloof as other ISxx types.
ISTPs? I dunno. I don't even know where to find my kin. As far as I can tell, if you want to find some ISTPs, you'll want to find them in a group setting. Unless I'm in a group setting, I keep to myself and may be unapproachable. I go into mountain lion mode if I'm out doing my own thing and don't want to be bothered.
ISFJs, couldn't say. I know there everywhere, but for some reason they're hard for me to spot too. I feel like they have a pretty wide range in the way the act and appear. I've seen programmer ISFJs, punk-rock ISFJs, too-cool-for-school no-nonsense ISFJs.... yeah, I've seen a lot of different kinds.
I've noticed ISTJs in a group setting can appear very ISTPish. Can't think of a good location to find them either.
I have an inner monologue that sounds strikingly similar to something off Animal Planet.