relationship relativity

A and B meet. A behaves like this to B, causing a "first impression". However, C a long term knower of A says A behaves like that to everyone.

Should B:
1) Continue with existing preception of it's relationship with A
2) Augment it's perception of A based on new information from reliable source C.

I personally pick option 1. Although C may seem to know A longer, his information is not useful in the relationship between A and B. What C says could be trusted information or it could be gossip or it could be C's augmented perception of A which C believes to be true. In the case of such uncertainty I'd find it safer to trust my own perceptions and discard C's information rather then act upon it.

Option 2 seems somewhat more the popular option, especially when discussing negative behaviour. Since A is like that to everyone, B should cut A some slack, A could be a nice person still. Notice it doesn't work as well with positive behaviour though, nobody says a bubbly person isn't bubbly because she (only she's can be bubbly i think) is bubbly all the time.

non-nerds please stop reading here
Apparently after long discussion with D we can conclude that option 2 should follow soemthing like this:
B perception of A, X, and C perception of A, Y, should be augmented considering A perception of C,I, to develop a final perception value of A to B, Z. To such effect as determined by one's personal weight function.

Z = X + weight_function(I) * (Y-X)
where weight_function ranges from 0....1
e.g. weight_fucntion(X) = atan(X)/90