These days most drops in G seem linkage related, but with no single predominant factor involved.

Traditionally we've taken a fairly narrow view of what might constitute a "link schemes for the purposes of improving PR or ranking", and I'm just wondering if we've been fooling ourselves by doing so?

IMO, apart from the traditional cross/interlinking, bought/sold links and any run of site links should also be included.

Among other things, I think maybe it could include any type of linking that's obviously to be for the benefit of rankings rather than for users as a normal part of content for a site. So that could include some types of doorway pages, even though they're within guidelines in other respects. I think it could roughly be defined as anything that appears to be part of a linking "strategy" to improve rankings that otherwise wouldn't be there.

These days most drops in G seem linkage related, but with no single predominant factor involved.

Traditionally we've taken a fairly narrow view of what might constitute a "link schemes for the purposes of improving PR or ranking", and I'm just wondering if we've been fooling ourselves by doing so?

IMO, apart from the traditional cross/interlinking, bought/sold links and any run of site links should also be included.

I've been of the group in the 30/30/30/10 rule is generally the best overall approach:

1. 30% some form exchange e.g. private link exchanges, directory with recip or self-control links [crosslinking]

2. 30% 1 way in or 1 way out e.g. industry associations, trusted feeds, informative resources, third party articles, etc.

3. 30% PPI one way inbound e.g. PPI in all its forms (Yahoo, other PPI directories

4. 10% link brokers - merely a variation of PPI and while I for a long time considered a less desirable campaign development - the versatility of this service (and time saver) cannot be so easily discounted.

A big CAVEAT here (IMHO) when and if using link brokers '1' link per website at the quality you can afford.

Avoiding the 'overboard factor' in all areas turns 'scheme design' into 'dream design'.

What constitutes a "links scheme"?
Shifty and tacky, no matter how sugar-coated with marketing hype.

Dunno glengara, you can just kind of spot them when you see them. You know in your gut somehow. They just don't smell right, kind of like bologna when the preservatives don't quite do it any more. Kind of slick and slimy feeling - it may look OK, but eat at your own risk.