Sorry, I was trying to stay out of this but I do feel the need to just weigh in a bit here. In my opinion, the default should be to just assume that any kind of physical contact is unsolicited. Heck, even unsolicited
advice gets on my nerves!
One could argue that the context and the environment could possibly dictate people's actions and how they think they can conduct themselves (i.e, if it's a club, assume that because of the environment of booze and hedony that people don't particularly mind being groped, or even approached - it's a social environment and people are presumably there to meet people, have a good time and possibly even something more). Even so, in my mind, someone could be stark naked and screaming for someone to initiate some sort of contact, be it sexual or no, and that (to me)
still doesn't then give someone the right to invade that person's space - I even become wary when people just stand too close to me fully clothed! It's just down to awareness, respect and common decency, and doing the right thing.
I don't think it's right or fair to put people into compromising situations. I agree (and have been there myself), that some people are unable to speak up for fear of rocking the boat; that
still doesn't make it acceptable to invade space or initiate some sort of physical contact. It's not consent. Even someone watching from a distance can report being affected by sexual contact/harassment, even if the person directly affected by it doesn't see it that way.
This won't be a popular view amongst some of you here (and it's off topic, I know), but even as someone who considers herself modern in terms of attitudes and values, I do feel that in this day and age, as a society, we're becoming more and more afraid to even scratch our backsides without someone reporting it or upsetting the PC brigade. Whatever happened to people actually taking responsibility for their own actions instead of continually pointing the proverbial finger at someone else (or the Government)? Warnings for this, labels for that! Good old fashioned communication has gone out of the window, and vague implications leave too much to chance, but in the case of asking for consent regarding physical contact, as
@Rui said - how hard is it to just directly ask someone if they're okay with it instead of just assuming that they'll be cool about it? In the experiences I've had I wish I could go back and just outright say "no" instead of just trying to awkwardly wangle my way out of those situations for fear of causing offence.