I think.....
The term "rare" is neither here nor there. What could be rare to one person (abiding to the correct contexts of the meaning of the word), may not be rare to another. Especially when we are talking about us, and vintage vacuum cleaners. Where one model, may be well sold, or often seen in one area, then may not bee seen at all in another. So that is a HUGE factor on the label of "rare".
Now, when I was a kid, in 1995- 2000, this is what I was told once about the meaning of the word Antique, versus Vintage and collectible. I was told by a dealer, that something that is Antique is indeed 50 years or older, keeping in mind, this was almost 20 years ago, and then 50 years was basically the early 50's. I was then told that the term "Vintage" gives the general understanding that we are talking about either kitchy types of things, and such from the later 50's and on through the 70's. The "Collectible" meant that age is not always, and is very seldom a factor. Because a collectible can be a brand new item. It is just often a special series of something that is marketed toward that particular type of person.
Now I will say, going back to the fact that was 20 years ago, things have changed a lot. People tend to use what ever term they think will make them more money, not what term would be correct for said item. That is a fact of greed and or ignorance. But that is how the general public is becoming, because of Ebay. No one wants to listen to a expert, or a dealer, or read a price guide to obtain correct, concise information. They think because someone is selling something on Ebay that they somehow know what they are talking about. I don't really understand how that is conceived, but seems to be how it is.