Matt Cutts: Does Google remove the PageRank coming from links on pages that no longer exist?
Topic: Does Google remove the PageRank coming from links on pages that no longer exist? – Quick Answer: Yes
Matt Cutts: Will changing the code and layout of my pages while moving to new URLs affect their rankings?
Topic: Will changing the code and layout of my pages while moving to new URLs affect their rankings? – Quick Answer: It can do. Do some tests on certain pages
Matt Cutts: Can a spammy website affect the ranking of other sites hosted on the same server?
Topic: Can a spammy website affect the ranking of other sites hosted on the same server? – Quick Answer: Don’t worry about it
Matt Cutts: What happens if I link to a good page that later becomes spammy?
Topic: What happens if I link to a good page that later becomes spammy? – Quick Answer: You’re ok if there’s just a few
Matt Cutts: Are all comments with links spam?
Topic: Are all comments with links spam? – Quick Answer: No