i have a google SHOPPING ad campaign going. unlike a regular KEYWORD campaign, the SHOPPING campaign provides no details about our products’ rank among its competitors that we are bidding against. for instance, there is no “Average Position”. so how am i supposed to know if i should be bidding up or down our different products?
You do not have enough information so you’ll have to take the risk.
Experience will play a big part here because maybe with other figures (number of searches, etc) you might be able to guess (literally guess) if it is interesting or not.
Something that you can do is to act like a user and see what comes as first results. Study those, see what’ve they done right (descriptions, titles, etc) and start from there.
Without analysis, you can’t decide. Check on google analytics as it is really helpful to understand which ads are working and which are not. Also check for leads as well.