"Complete upper" is nomenclature that is dubious at best. Some people consider that to include the BCG/CH, some don't. Most of the site sponsors and vendors do not consider a complete upper to include the BCG/CH, unless they state it specifically. This is why you need to actually read the ad and see what is specifically mentioned. If it isn't specifically mentioned, especially with a picture that does - well, we're treading the line here and I'd say the seller is in the wrong as he is intentionally (or not) misrepresenting what is for sale - especially on something as easy to remove as a BCG/CH. Needs to be spelled out - and if you are unsure, to ask either via post, PM, or e-mail. Definitely caveat emptor.
A true bait and switch, would be a seller advertising a 1/7 chrome lined 16" barrels for sale, with the specified intention of running out of stock quickly (or even not having stock at all) and offering to "replace" it with a 20" 1/9 unlined barrel. Or having an ad spell out one thing, and leading to a website store to order to a different item (similar or not). There are a ton more examples of bait and switch scenarios, so I'll leave it at that.
The seller needs to be clear with what he is selling, and the buyer has to understand what he is buying. Especially when the definition of terms varies as it does in firearms, regardless of your opinion if you think it is correct or not. If I post "charging handle for sale $10" and do not provide a picture and you jump on it... when it shows up and doesn't include a latch, spring, or roll pin. Will you be pissed? I didn't say it was a complete charging handle, I just said charging handle. You'll probably get a split opinion on who is in the wrong, as you could make a case very well for either side.