I don't think everything is tell-tale. There is usually some sort of group of mainstream cultures in terms of dress and styling, and there are usually outlying cultures of dress and styling. I think it's as simple as that. It's like a bell curve. Kids might do alt stuff to try to be unique (thus the whole joke of conforming to nonconformity), but otherwise people do it simply because they're attracted to the styles, or to feel community with the people they're around.
I just put on a retro pin-up avatar before responding to this. Why? Well, because I'm silly with avatars, but I can make a point with it. I like the style. I have a lot of vintage and vintage-looking clothing. Does that say anything deep and profound about me? Of course not, it just means that I like a thing. The same thing goes for other means of presentation and expression.
If someone has a lot of tattoos, chances are they're just more associated with a subculture that values them as a means of expression. It doesn't make anyone impetuous or misguided, and this whole moralization of every little thing people do just leads to completely unnecessary judgmentalism. I would argue that judgmentalism is more of a vice than any of these things you're trying to pass unnecessary judgment on and trying to fill with nefarious meanings that just aren't there.
As for tattoos starting with gangs and sailors, so what? It doesn't matter where things originate or end. Makeup started with rich men, for instance. So what? Let people enjoy things, for crying out loud