Totally agree. I try to stay completely detached from my characters and dialog. If I think I might say that in the situation, I change it. If I think another character may use "that particular wording" I change it.

Allies tend to pick up the same speech, but they maintain the nuances with regards to their personality.
One says "F," the other says "crap," another may say "son of a b" all in response to a tire blowing out on the way to an interview. It doesn't need to be categorized though just use different ones for different characters - maintaining continuity of course.

I will use my philosophy as an over-arching theme, but that's it. By detaching you can imagine other people's reactions.

That's most of the fun.

I don't think we can avoid inject our philosophy into our writing. But if we have a broad range of understanding about different believes and philophies, we can also inject them into characters. One of the best compliments I got on something I wrote was that if the names were covered up, you could still tell who was talking. I thought that was pretty cool.