Regarding directories: Would it not be better if google had a consistent policy regarding the value of links from paid directories?
I believe that Google does have a consistent policy, mentioned it the second post on this thread. It's just that there's been so much evolution in search in general that the details can get hard to follow sometimes. And the details do change, or rather they get refined... but I don't think that these have.
There are several well-known paid directories that charge for review and for editing. I won't mention their names here... but note that the review and editing are key components of why Google allows them.
The review is to check your site. You are not guaranteed inclusion. In some cases your review fee buys you a retry option.
Editing includes both the editing of your submission and the ongoing editing of the directory itself. A well-edited directory is well-categorized, puts you in good company, and most important, makes the content of that directory unique enough that it's not simply cookie-cutter dupe content.
Assuming that the directory uses the fee to maintain a certain level of quality, Google does not
consider these links paid. There aren't many directories on my list that pass Google's test.
I should add that from what I've experienced, if directory listings aren't confirmed by other signals on the web, the temporary boost you get from them is likely to fade.