I know its good to have relevant links but does it hurt to have links that are not related to your site? For example, like a basketball site linking to cooking site
If your only interest is in pr then you may be able to get away with it. Most sites that rank well will have quite a few links from sites that are not relevant so it will not hurt that much, but of course it is better to have relevant ones. As long as you can get the anchor text that you want you should be ok though.
pr links are quite good and can be snapped up for fre from directorys,free accounts like Digg,Myspace,Delicious and Deviantart ect....
Inbound links (no matter how bad they are) from any sites will not hurt you You may want to refer to the following thread for more details: http://forums.digitalpoint.com/showthread.php?t=166583
i think that "bad" inbound links do exist. Why? logic. if i was a search engine, i would use my algorithm to determine "bad neighboorhoods". this means that if your site links out to a casino site or porn site i would penalize you. not if their was just one link casino site to your site, but if i see a pattern and a lot of "bad sites" link to you and you link to shady sites then, yes, i would slightly penalize you. this is the reason a lot of link builders will NOT buy links from sites that link out to "bad" sites.
Bingo. If there isn't much negative weight, if any right now, there will be in the future. Google doesn't like people purchasing text links really. So when you have two websites not at all related, it will raise a flag from Google that you're trying to trick their algorithm. But then again, they don't know if both the sites are yours and you're simply linking to another site you've made. I think Google will get smart enough to decipher this in the near future. Just stick with relevant links. Don't waste your time with anything else.
From my experience I can say that not matter the irelevant links to your site but the number and the quality of RELEVANT link is very important. So, get more relevant links!
The key is having good anchor text from the nonrelevant links. If you don't have good anchor text they aren't worth much.
What about bad neighbourhoods, spammy sites, link exchanges and SEO related sites that google themselves have said we should stay away from?
As what has been mentioned by other members. Google and other search engines do not penalize your site even if there is a super spammy bad inbound link to your site. Why? The reason is that Search Engines want to prevent sabotage. If a link from a bad site points to a page and it affects the SERP, then competitors will have another way to exploit the ranking nature (by placing their competitors' links in the bad site). Search Engine understands that the webmasters do not have control over this kind of link manipulation and therefore, do not issue penalty in such case. SEO gurus like Peter Kent and Dave Taylor have also talked about this point in their SEO books
It can hurt but it depends on semantics of your backlinks and how good google knows about your site(s) setup.
Irrelevant links may only help in terms of PR. This will not affect your ranking on SERP's. Google's focus has been the usefulness of a site to users. So get only links from related sites.
I really think it depends on whether or not you're just farming links, and it has to do with whether you are posting the links or if someone is posting links to you. If the links are to your site, you can not control them so unless they are located on questionable sites, you have little to worry about there. It can actually help your PR. If you are posting a huge mass of links on your personal website, you are getting into a gray area and should select only relative ones so that there is a clear definition of what your site is about. Feel free to clarify the direction of mentioned links so we can give you advice accordingly.