Nobody should worry too much about those + and -.
Keep in mind that they are done anonymously, usually by the same few people multiple times and without the need for a valid reason (if people had a good reason for them they would have expressed it in a post reply).
In the end, those + or - are not really an evaluation of the user that receives them, but an evaluation on the people who do the voting, the amassed average forum readers.
When these +/- votes are given for the wrong reasons, it does not speak well for the readers. For example, a poster spreading popular misconceptions and superstitions may receive lots of +s because these are common or popular views, while another using reason, logic and truth might receive lots of -s, because people often feel invested in their initial views and just don't like to have them challenged or corrected (people willing to listen and reason are less likely to still have naive views to begin with).
So again don't worry too much about the number of + or - you see. If someone had a good reason to disagree with you they would have posted it and explained it.
