Note that “unusual and not documented” does not mean “wrong” - many should be simply documented.
Some may be fixable remotely:
clear typos (shop=suupermarket)
written in language other than English but with clear mapping to local language (for example shop selling meat in Polish is “mięsny”, so shop=mięsny is clearly shop=butcher)
too specialized tags (shop=coal is better tagged as shop=fuel fuel=coal, shop=office_furniture as shop=furniture furniture=office, shop=indian_spices as shop=spicescuisine=indian)
very clear duplicates (shop=hypermarket vs shop=supermarket)
shop with website, maybe even linked in OSM object, that allows establishing proper value of shop tag
in some cases something is clearly not a shop (shop=factory_producing_widgets is likely man_made=works)
needed and valid shop value that should be documented at OSM wiki
Some may require resurvey, if one is luckily in your area you can check it. Or you can create a note and wait for local mapper to resurvey it.
Contacting original mapper may make sense.
Remember, it is better to not edit than break data in case of tagflidling - create note if unclear or unsure.
Let me know if this list is useful but outdated (I will setup refreshing it in such case) or pointless/problematic (I can delete it if it is causing more problems than benefits).
Some improvements can be made to this list… Mayvbe mark cases with nearby notes opened already so these can be skipped for now? And mark cases where website link is available so these can be processed first?
Cases on "entries from list of suspicious ones: " list can get explanations why this values are treated as invalid. Maybe more.
(helping here is useful as it allows to reduce number of not needed and pointless top-level shop values, on 2023-08-14 we had 11 215 distinct shop values, vast majority bogus, broken or not needed. Reviewing such lists also allows us to spot missing shop values, problems with documentation and presets. Repeated appearance of shop value may indicate that wiki or presets should be improved. Maybe iD translation is bad or requires additional aliases for easier search? Maybe OSM wiki would benefit from translating it to local language or being more clear?)
(I can also generate such listing for other areas, let me know if someone is interested)
I looked at the suspicious ones and changed most of them to more well-documented types. I added one note and kept the ones for coffee_machines because that’s exactly what they specialise in. I changed one machines shop back to knitting_machines also because that’s exactly what they’re selling (Osmose seems to have highlighted it as a mistake, which it isn’t; I added it myself). I did find that the labels of the knitting machine shop and the flags shop were swapped, however (they are neighbours). Some shops are extremely specialised so I think it’s better to create a new tag value for them than to inaccurately describe them with a more general one.
Wrt. the other list, I think I’m responsible for some of them. There are quite a few shops in Bulgaria that specialise in cleaning products (washing powder, etc.) because they were apparently in short supply during communist time and entrepreneurs jumped into that gap in the market when that became possible. Surely these shops also occur(ed) in other East bloc countries (remember seeing them in Hungary in 1989)? Maybe this type should then be documented?
There are 3 shops in the list that sell laboratory supplies, chemicals, etc. Maybe this type should also be documented? I’ve seen them in Turkey too (I’m a chemist so I happen to notice them). Same for the packaging shops: they’re of course mostly B2B, but they are shops where anyone can walk in and buy something.
Adding main tag + subtag also may make sense (say shop=greengrocer greengrocer=fruits if shop sells solely fruits seems better than trying to get shop=fruits supported, similar for say shop=seafood seafood=salmon for shop selling solely/primarily salmon)
no opinion on other shop types (maybe there is already tag for them, maybe subtags would be optimal, maybe new shop value) but shop selling packaging supplies definitely exist and seem to miss a matching shop value
(list update may be a bit delayed, I am travelling - in fact, I am writing this reply from a bus and updates are run from my laptop)