yes broken link affect very much bcoz crawler cant able to move ahead due to broken link, so w3c validation will required and all html errors should be removed for better ranking
Its logical , ethical or simple to answer, it will effect badly , FIX it anything broken links or things or products or human's body is not worth so you need to fix it As mentioned by lindamood , Spiders wont be able to crawl
I agree. Search spiders will crawl your site, If they find some broken links, They can not crawl further, So It will affect your position in the search results.
I agree w/ everyone here that it can affect the crawling of your site. Since the link cannot be followed it can also affect the Page Rank of your site since your URL is not getting credit for the inbound link and can also affect your rankings since you are not getting credit for the inbound link text for instance.