The link is a perception one. To people who view those original statements as negative ones they're not going to care about anything positive and the positive ones won't minimize the negatives ones for them usually. Therefore, if there are negative statements generally some people will find that they outweigh any positives said.

I assumed the link was pretty obvious... to paint a vivid picture if you have a person or group that says nice things most of the time about puppy dogs but just once says some hateful nazi rhetoric, someone out there will find that the negative outweighs the positive and won't care that there are positive statements.

Edit - I probably should've qualified my statement in my original post to better state that position. I can see now that it seems my statement is an absolute for all people. Not my intent.