This bothers me generally. If someone has an obnoxious laugh (or voice for that matter) you're not sure whether to tell them to shut up please or stop doing whatever it is you're doing or saying to make them laugh. This has nothing to do with tickling really it seems, and more and more to do with whats tolerable in a person enough to be in their presense as just a friend or more regardless of what you're doing with them.
If something as simple as their laugh or voice is already obnoxious and coarse, even if they have no control over it, then I imagine it would ruin a great many things in your dealings with that person. They could be sweet and nice, but if its just plain hard to tolerate them then its a real problem.
I know that sounds really, really, REALLY shallow and superficial, but lets face facts people, if something bothers you you aren't going to tolerate it unless you don't care whether you suffer for it or not. Its just like the looks thing. Looks are initially more important than anything else because looks are all you have to go on (unless you count spiritual attraction by way of auras, etc.)
If they aren't good-looking (to you), you aren't going to approach them or take a chance or gamble with your feelings like that. Its not until after you meet then that you can discern whether or not this person is for you and should be in your company or you in theirs.
An obnoxious voice or laugh is just as much a viable handicap in this process as looks and appearance are. If you can hear someone's obnoxious laugh from the other side of a room and its a party and their voice is louder than everyone else's and it drowns them out, you're telling me thats not something to think about? Think about all your dealings with this person. If thats their natural voice, they're going to be like that all the time, no matter what they say. Thats not just obnoxious, thats embarassing, and its sad because it's not their fault.
I think what makes it hard for men to accept this in women is that women aren't supposed to sound like that. They're supposed to sound feminine, delicate, and have soft voices with different tones. Anything that clashes with the femininity of a woman, such as weight-lifting, smoking, alcoholism, etc, hurts them overall, and a disturbing voice is no different, even if the other examples are double standards.
Its not fair, but a man can get away with a lot of things a woman cannot. And we live in an age where looks are very decieving. But alot of people I'd imagine, if they're being honest with themselves would be put off by someone with an obnoxious voice or laugh.
Its really uncomfortable to even have to think about it, because its embarassing for everyone involved, but even in a social setting its bad. Theres no easy way around this. Unless they can change their voice somehow or take voice lessons. But should they have to do that just to be acceptable company for others? No.
Finally, I've never been in this kind of situation, so I don't have to worry about it.
This doesn't have much to do with tickling, but I think theres more to it than whats been initially suggested, especially in a much broader sense.
I wouldn't judge a person because of their voice, but I can't honestly say I'm big enough to want to be in their company if they themselves sound obnoxious whether or not they are. It would sort of be like having brunch with a serial killer. Sure, they may be carrying a conversation well, but you can't help but be preoccupied by the fact that they've murdered folks and they may kill you in moments. A loud or obnoxious voice is just as unavoidable. All of your attention goes to that and its hard to channel it out.
I think its important in how people deal with these situations. I can only presume to say what I THINK I would do in a hypothetical situation, but even now I'm not sure.