I wanted to find you a few links that may be interesting, though they are purely exploratory on my part...I am just starting to read them in more depth...
DISC is a very, very popular personality assessment tool. (also known as the "color" test, or Insights). It isnt copyrighted, so pretty much anybody can build a test based upon the method and then use it as a consultant tool. It is more commonly used than mbti as it is simpler.
In DISC there are four types of interaction styles-D, I, S, and C. people typically display a combo of them. I misunderstood the DISC theory at first as I thought is was jungian, but it was developed by another guy in the 20's: http://www.discusonline.com/udisc/default.htm
In DISC a person who is very high on the "I" scale, called an Influencer, displays a lot in common with EXFPs, and some IXFPs: http://www.discusonline.com/udisc/i_influence.html
When I dug a bit deeper into the original guys writings (http://archive.org/details/emotionsofnormal032195mbp) he really spoke much more about how the D-I-S-C types are actually modes/methods of communication. The "I" mode he called "Inducement" and it does have some very distinct manipulative tendencies, but mostly unconscious in nature (http://archive.org/stream/emotionsof...e/n15/mode/2up).
I'd speculate tentatively that the inducement corresponds to some of the communication techniques used by FPs that can be seen as moderately to extremely manipulative from the Ti-Fe perspective and feel rather odd. When I communicate....I explore the conversation not paying attention to words, but rather visceral feel tone, and an odd fluidity, a lulling and pressing back and forth...diving in and out of the other person and wrapping around them...totally using tone, voice, and vocal intensity to influence the listener...like you are weaving yourself into their space...
so, I dunno, maybe you are sensing some of that and because it is so different, it just feels really weird. (Could be bullshit though as well.. )