Here are some questions which have been asked by users on the internet about error 404's, this article is useful to know if these type of pages will damage the reputation of the site.
- Do the 404 errors reported in Webmaster Tools affect my site's ranking?
- So 404s don't hurt my website at all?
- Tell me more about “soft 404s.
- How do I know whether a URL should 404, or 301, or 410?
- Most of my 404s are for bizarro URLs that never existed on my site. What’s up with that? Where did they come from?
- Can I use Google’s URL removal tool to make 404 errors disappear from my account faster?
All of these questions are answered here