Believe me, that's probably true. On the other hand, just for once, there might be a significant number of people actually sympathetic to me, due to the show. Maybe I should sponsor it myself.

Lets drop the loud music argument for the moment. Why can't I deliberately block you car in with two of my own. Why can't I take stuff from your trolley as long as the supermarket don't stop me? Why can't I follow you around town calling you a stupid w**ker just cause I feel like it?
I'm not quite following your argument. Are you claiming that the only reason I can't do that is because I'm deliberately trying to annoy you? Or are you saying that it's perfectly reasonable to do those things.*
It's late so this may not make much sense.
To the first question I'd say 'yes'. The goods are technically the supermarket's property at that point, until you purchase them at the register. If the supermarket says "Don't take stuff out of other people's trollies", that should be as valid as "You break/open it, you buy it." Still, the first thing that people do shouldn't be to report them to the police. (I assume you're talking about "carts" in supermarkets)
Following me around town, I'd wonder why that person was going to waste their time doing that.

But I would say it lies in a dark grey area too, as long as I'm in public places and/or the owner of the establishment I'm in is indifferent to that person's presence. On the one hand, they technically have the right to call me a stupid wanker. On the other hand, they're obviously abusing that right to harass me.
To provide an analogy to the masturbation thing, you'd have to have the guy following
her around town masturbating. For the sake of the argument, I'll assume that does happen. Obviously my first thought is "Eww". But I can't think up any good reason to demand that he stop other than I don't want to see it. And while I would love for things to go my way in the world (at least for a little while) I know it's not going to happen, and it's unreasonable to expect the same of everyone all the time, because I'm not going to do it for them either.

I
think I've gotten my idea across. (If not, I probably won't, ever) Now let me totally destroy my arguement for public masturbation.

On the other hand, the guy's spreading bodily fluids, which is a known way to spread such fun diseases like Herpes and AIDS. Even if he goes to wash his hands, he's going to have to touch the faucet, the door handle, etc etc. If the guy were to actually have one of those diseases, he could pass it on to an unknown number of people. Say, the person who used the bathroom after him. The actual probability is probably VERY small of that actually happening, but the types of diseases usually spread are usually of the life-threatening variety.
If public bleeding constitutes a health hazard, then so will public masturbation.
However, my point here is, even if there is a public feeling that something is 'bad' or 'wrong' or 'unacceptable' or what have you, it should not mean that people should run out and legislate a law for it so they can prosecute other people. If there's a good reason for it...but otherwise I think that personal liberty should take precedence rather than freedom from liberty.