not2easy - 4:55 pm on May 27, 2012 (gmt 0)
I don't represent all affiliates, but AFAIK the preference is for all products. An affiliate may specialize in discussing the best cabinet hinges and have side information about cabinet tops for example..they wouldn't want just the tops. You never know when a shopper starts looking for one thing and ends up buying something entirely different. If the purchase experience is pleasant, they will be back for related products when they have a need.
More important than which products is making sure that they are properly categorized. Too often everything from shower curtains to staple guns are listed under something like Household Supplies. If your business is all one category, it would be more useful (to you and to affiliates) if it had proper subcategories. Sometimes I spend days to manually fix a feed so that it can be expected to attract traffic.