I think there is value here, when it comes to products or restaurants.

For example, u could do a weighted average, that at a glance shows u relevant information.

Instead of having each review/rating have the same weight, one could give more importance to your follows.

e.g. your follows have weight 1. npubs 2 hops away have weight 1/2, then 1/4 and so on. The idea is that people closer to u will have an opinion that is probably more relevant that people far away from u 

 You could also value to the rating of npubs that like the same things you like more. 

 yes, but that can be tricky against targeted attacks.

Like, I wanna make u buy this thing, so I'll spin up millions of nibs that have precisely your interests, so I'll skew your ratings. Unlikely, but possible  

 it wouldn't take much computing power to produce those events, but relays might reject them as SPAM if they have old timestamps.
Hopefully we could do an ok job at identifying the spam, between relays, WoT analysis and even more sophisticated WoT analysis done by DVMs. Thinking more about it relays are pretty incentivised to do good spam prevention. we could select relays we think are doing a good job at it and use them rather than using DVMs too much.