Thanks for for your feedback guys! It's greatly appreciated
As I mentioned on first instance this strategy screamed Black Hat at us. We decided to carry out some research in to 302 redirects to see if anything cropped up. The general consensus was that 302 redirects were not harmful for SEO and did not pass any link juice. So this planted a tiny seed of doubt in our minds to completely categorizing this as black hat. So I came to the SEOmoz community to get some concrete answers and you guys confirmed our initial thoughts.
At the moment based on your feedback I think we wil recommend culling the irrelevant domains and redirecting a couple of the relevant domains to an affiliate site and then redirecting that site to the main site (just like you suggested Shledon). I completely agree with you when you say relevancy is key.
Any more thoughts on the issue are more than welcome..
Thanks again