I've been selling directory listings (advertising) for over eight years that just happen to have direct links to my customers website.
I haven't noticed any problems with my rankings or my customers..
Just for the record - my listings are on subject matter and well matched to the relevant keyword/industry/subject - nothing spammy..
Here are a few examples of organizations that sell advertsiements with direct links.
NONE OF THESE SITES ARE MINE..
Business dot com
Thomasnet dot com
You folks seem to be operating on hearsay..