People will always vote however they want, you can't apply any control to this - if the post is helpful to the person reading it, it is their prerogative whether they upvote it or not. With this in mind, your actual question should be:

##How do we deal with highly voted but incorrect answers?

Well, there are multiple ways to deal with a highly voted but incorrect answer!

- Downvote it for being incorrect
- Post your own, correct, answer
- Edit the current highly voted answer

A couple of things to note: 

- Radically changing an answer is frowned upon, if the answer is really that wrong and it's because of a misunderstanding of some kind rather than a patch that changed the way functionality works, then downvote it and post a new answer
- If a post has been outdated as a result of changes in the industry, methodologies, software patches, firmware updates, etc etc etc - you can either edit the existing post and clearly state #Out of date as of `<date>`/`<patch>`/`<cake>` before putting the updated information at the top of the answer, or you can post your own answer clearly stating that your information is valid as of `<date>`/`<patch>`/`<cake>`