That's the connotation of tolerance, unfortunately. Not it's meaning. Unfortunately, you're right, tolerance tends to turn in to contempt.
I think it's because tolerance attempts to hem itself in to acceptance. If tolerance sort of just stood as is finding objective reason, while still allowing one to have an opinion about something the world would be a fucking amazing place.
Imagine a world where one group they can say "man I fucking hate that other group, but they still deserve their rights."
I just think tolerance and acceptance are two different words that people seem to confuse most of the time.
Tolerance; a fair, objective, and permissive attitude toward those whose opinions, practices, race, religion, nationality, etc., differ from one's own; freedom from bigotry.
Acceptance; the act of taking or receiving something offered.
ie, I may not accept the gay life style, but I'll tolerate it.
I don't like that we have to accept every fucking thing we may not agree with or be drawn to. It's every persons right to say "no sir, I don't like it." yet some how if you say that it makes you a bigot. That attitude infuriates me just as much as those who persecute people for their differences. It's two different sides of the exact same coin.