Reasons stand on their own merit.

If you get six times a -- because "the voter doesn't like you", but you don't know who it's coming from, does that mean someone has a deep grudge against you? Or are you just generally unpopular.

It doesn't matter. It has no merit.

if the -- vote is because "I don't understand the post", does that mean ... your post is really unclear?

You look at your post and determine whether you should have been more clear. If you think you did a good job, nuts to the downvoter. It doesn't matter who they were. It's not going to help you to know that someone you respect thought your posting was gibberish, if you don't agree that it's gibberish.