I envision a panel of emoticons akin to the Facebook reaction set, but where the user can select as many as they want to quickly convey different combinations of their reactions:

    (thumbs up)      I liked this
    (heart)          I loved this
    (thumbs down)    I didn’t like this
    (smiling face)   This made me happy or satisfied
    (frowning face)  This made me sad or disappointed
    (surprised face) This made me surprised or impressed
    (angry face)     This made me angry or frustrated

Of course, it gets complicated. Did Sam U. Zerr give that product an (angry face) because they used it and didn’t like it, or because they’re offended that you would recommend it, or what?

If you’re only using icons to make recommendations to an individual user based on their own history, maybe you don’t need to infer the actual meanings; you can add all sorts of icons without any particular meaning and just make recommendations by correlation:

    (thinking face)  I’m considering this / I’m confused by or dubious of this
    (gear)           This was useful / this made me think
    (fire)           This album was great / this sauce was spicy
    (heart eyes)     I really want this / this is adorable
    ...

E.g. a recommendation for me might be “(thumbs up)(gear)(heart eyes)” because some product or content is similar, by some hidden metrics, to other things that I’ve reacted to in those ways.

Just brainstorming here. There are obviously many possible approaches in this space.

Put differently, a set of binary choices: amusing, interesting, sad, ... It's a bit difficult to come up with a good set to rate any thing, but I can see it working for specific topics, like movies or games.

Or, one could just let users tag the subject and the interface would display the "weights" of the tags.

That's part of the problem here. Appropriately rating different types of things differ in various ways.

A simple utilitarian object? It mostly works or it doesn't.

A movie? Just to start with, there's the rating of the movie itself vs. the rating for this particular DVD. And then there are the dimensions on which the movie itself could be rated.

Or you just throw your hands up in the air and either do a thumbs up/down or a 5 star rating system on the grounds that it's better than nothing.

How about vision based emotion recognition of viewers with cameras in the televisions and monitors? Sure sounds creepy and behaving different when observed etc. But I believe people will forget they are "observed" so the effect dimishs after a time. Than we would have a quite honest emotional feedback for movies. Even for specific scenes, for advertisment, etc