It use to be very common. Now it's a lot less common, but given the right industry and corporate culture, it's still not that hard to find.
A comment or two here and there, or an infrequent occurrence that is not dramatic, is unlikely to be considered sexual harassment, and would be difficult to pursue legally. If someone flirts and makes an advance, and you rebuff them, and nothing affected work other than the awkwardness, it probably wouldn't be something anyone would get in trouble for. If they had authority over you...its a little more troublesome, but if it was an honest interaction that ended in fairly professionally recourse and no punishment or demotion, etc., again I think it wouldn't be pursued or pursuable.
The thing is, that "light" stuff should be discouraged at all levels of the company to help ensure it never gets out of hand, so that no one feels the company turned a blind eye to it, etc.
Some companies may have zero tolerance, if you date or kiss or anything with a co-worker, you're out. This is a private decision, not related to sexual harassment laws directly.
The biggest differences come in with regards to how you are treated in the workplace. If it's a boss or authority over you, and its always or often accompanied by flirting or talk of sex, it's probably harassment. If it goes over the line and it's quid pro quo (I get this, you get that), or involves any threat to fire, demote, etc., it's harassment. If there is a lot of porn in the office and sex talk all the time...I mean, you could quit, but ultimately that's a hostile work environment (unless you're in that industry I suppose!)
I suspect in Fox's case, it's probably all legit sexual harassment. This is not the first time this has come up, and its all coming out now that from the top, it was normal if not expected, and almost all of this involves positions of power over individuals, and a fair amount of blatant quid pro quo. Claiming it's just about a law suit, is irresponsible.
We need education and awareness, and yes, some high profile examples made, that helps set out the groundwork for good workplace behavior. Fortunately I had good training and avoided a number of potential harassment situations when I was the boss of a few adventurous women who were not shy. For a man in power to reject the advances of attractive women in private...is asking a lot of men (speaking as a man, I'm sure its that way for any gender vs gender). Which is why you adopt at least some basic guidelines like having glass on the doors, no individual man/woman on a business trip (unless you're 100% sure its not even close), and ensure that no one talks sex in the open, and that people who do are corrected (nicely, indirectly) etc. Once aware of it, you can use common sense. But without awareness/training, etc., common sense when a women you like advances on you, is to accept that it's your lucky day.