I agree with much of what has been posted so far... but I do want to clarify something.
First, there is a difference between 'Prejudice' and 'Dislike'. To be prejudice means (literally) that you are 'pre-judging' someone without any evidence to substantiate. I have lots of 'F' friends with whom I have a great time and whose company I thoroughly enjoy. I know other F's that drive me absolutely insane because they are consistently blowing things out of proportion, getting upset/angry/sad (etc etc) because of MINOR things. They are unable to step back and see that it isn't a big deal and this type of behavior makes me want to smack some sense into them. These are usually the ones to whine, whine, whine about their situation but refuse to take any action to correct it.
I don't automatically assume that just because someone is an 'F' that they're an oozing mess of hypersensitivity, but I DO alter my answers sometimes to be more sensitive and say exactly what I mean to say rather than risk being misunderstood. In this way, I am 'prejudging' from experience, knowing that if I give a curt, short answer or fail to give a pat on the back when its due I am perceived as rude, even if I don't mean to be.
In this case, I don't think it has anything to do with them, but rather with me and my own awareness of how I interact with others.
I respect someone who can make CONSISTENT decisions about their life and their values based on their feelings. The ones that baffle me are the ones who do completely opposite things every time they turn around, with no real sense of who they are or where they stand on anything. This kind of 'waffling' of emotion-based decision making is difficult to witness. They're like a bouncing ball that doesn't follow the rules of gravity or inertia. Where you think they'd turn left, they turn right, and all of the decisions seem to be done by the flip of a coin. I tend to avoid these people wherever possible. They make my head hurt trying to figure them out.
With regard to 'dismissing feelings' as invalid, I learned a long time ago not to do that. All through my childhood and adolesence I routinely hid my emotions and bottled things inside of me. In my early 20s it started to catch up with my physically, holding so much un-dealt-with tension and stress inside of me that it was making me sick.
Once I finally realized that I had to deal with the things I was feeling it was like an avalanche started. Things that I should have dealt with years and years ago but never did bubbled to the surface, and I spent a few years straightening out my hurts and motives.
Nowadays I find myself trying to reach out to people more... offering support where it is needed, or even picking up something for a stranger who dropped it. I try to call my friends more (even though I'm sure its still sorely lacking

) I ask people about how things are going in their lives and I try to share more of myself without people having to pry it out of me.
All of this has taken time, but it has been well worth it. Of all the defined MBTI functions to try to have in balance, I think that the T/F line is one that should be brought as close together as possible.