[amr]

I think your are on to something. Report how many people saved a recipe (and unsaved it?), how many printed it and how many views it received.

Additionally, I think the mentioned websites ignore an important fact about recipes: they are not static. Most recipes have variations in technique or ingredients. Many cooks, as you stated, substitute ingredients that subtly, or not so subtly, change a recipe. If a mechanism exists to capture those variations (wiki style, maybe?), those people might have an incentive to come back and share their experience rather than their impressions.