This is one of those things were it is all by degrees.

Fuck has made its way into the british language such that if you don't use it, it just doesn't sound right.

Swear words, are used by most people with a decent vocabulary like you would use seasoning in a dish. It adds flavor. But, then you get someone who uses seasoning as the dish, and its horrible, obnoxious and unpalatable.

Also, we use these words to define how agitated we are by whatever has/is happening. So, a person swearing is considered more upset then a person who is not. But this is thrown out the window when you encounter a gutter mouth. And so, it is uncomfortable, because you brain is telling you that this person is about to pull out a knife and start cutting people up.

I tend to never use swear words, as there are better descriptive words that can be used instead.