I have 2 queries which I have been unable to find answers for on the web.
I am hoping someone can shed some light on these 2 issues which have been puzzling me this last week.
The first issue is same ip backlinks. I already know that obviously different ip backlink carry higher value. I also know that search engines will only index a set number of backlinks on any given ip. Ok so the question is; are all links crawled and valued and then a set number indexed or are only the indexed links on the same ip crawled.
The issue came about when I recently stumbled across a parking company. This company has 98,000 sites on 1 ip which are parked. The sites run some form of ppc and contain enough content to maintain pr. The sites range from pr0-pr6 from all manner of tlds and each have a links page where you can get an easy linkback.
So here are effectively 98,000 easy backlinks to get; but they are on the same ip. At what point does it loose its benefit and more importantly could this idea harm a site. :?:
The second question comes after discussion with a so called seo which has again left me confused. It was regarding pr0 backlinks. PR0 baclkinks obviously do not carry much value unless they are traffic generating. What the SEO was trying to say is that pr0 backlinks are potentially damaging to any site under a pr of 6. Once you get pr6 and above the percentage or number of pr0 backlinks does not matter. I was wondering how much truth there is in this.
As I mentioned I have found little content about these issues over the past week. I hope this thread can create some good discussion which I can join in with.

I can't really answer your first question. I don't think anyone who doesn't work for Google really does know the answer. It's all trial and error, and Google constantly changes their algorithm.

To answer your second question, it has been said for quite some time that a PR0 backlink can be damaging. There are two types of PR0 sites ... new sites which haven't yet gotten on Google's radar. These sites are fine. The second type are sites that have been banned from Google and now have PR0. A link from these sites can be damaging because it is like a link from a "bad neighborhood" ... in Google's eyes, you're now associating yourself with this site, which might have been banned for engaging in black hat SEO techniques, or being a link farm, etc.

By PR0 I mean a pr0 link page not necessarily a homepage. A lot of directories pages dropped pr in the latest pr update. I would never seek a link from a blacklisted site.

Just make sure to differentiate a link page from a link farm and you should be fine. :)

FYI, no backlink will ever hurt your site. If that were true your competitors could put links to your pages in link farms and other "bad neighborhoods" and hurt your rankings. The worst a link can do for your site is nothing. It simply doesn't help you in any way.

Thanks for your replies.
Regarding the 90k sites all of the link pages i have seen have under 10 links and many have no links. In this case I am getting a pr5 or similar link on a page with only my outgoing link. I think I have found a gold mine but just wanted to check it out with other webmasters first.