Question about online listings, VIN check sites, and model mismatches

I'm in the market for a manual transmission convertible Mini Cooper. When I was a senior in HS I saved and bought a manual 1964 Dodge Dart convertible and had a blast with it and didn't get into too much trouble. It wasn't super reliable, but it was fun. I've also owned a couple of MGs and Triumphs over the years.

My son is 16 and will be a senior next year, and is a great kid. I'd like to get him (really both of us) a used, convertible Mini Cooper S or JCW to have fun in. I don't know if we want to spend for a 2014+ one, so we'll likely end up with something not exactly reliable, but it will be a good education for all of us.

I'm browsing online listings on sites like carguru, autotrader, craigslist, etc. So many of them are listed as Cooper S or John Cooper Works with the VIN given, but when I use one of the VIN lookup sites it doesn't seem consistent with what they are. Either the HP isn't right, or the model doesn't come up as a John Cooper Works or an S. I know the JCW thing is sometimes tricky because for many years it was an install kit that dealers could install separately, but it seems dubious that out of so many listings that say JCW I've only found one with a VIN that decodes as such. Maybe sellers are just checking boxes that they don't know what they mean when making the listing?

Are the online VIN checkers pretty accurate in the experience of the folks here or are they sometimes off and the seller description more accurate?

It makes me feel like I really need to get educated about what to examine in detail when I go to look at the car to make sure I'm getting what they say they're offering. Also makes it impossible to buy remotely and have it shipped which is probably a bad idea anyway, but it's also hard to justify a 3 hour drive to go look at something that isn't what they're advertising.