dave - lots of old stuff, so gets a pass. gives back his test units or are ebay purchase (impartial).
Some I buy myself, some I give back as they are loaners, some are on permanent loan as demos.
I don't want to sound conceited or anything like that, but a company giving me a new scope, no matter what the price, it's kinda yawn worthy, I've got so many scopes I don't know what to do with them all. I don't feel the least bit like I'm being paid at all (and I'm technically not, because it doesn't put food on the table). If anything when a new scope scope turns up out of the blue, it's just extra pressure to actually get around to doing something with it. Most gear sits there gathering dust. I treat all gear as being on permanent loan, and they can ask for it back at any time.
There are very few instances where a company has said "we'll let you keep it". They simply send it to me and it's usually unclear whether they want it back or not.
It's actually important for reviewers to keep gear like this because then they can be used in comparisons and demos etc. I've done many such videos that would not be possible without having all different brands.
And I'll often include comparison with other brands in my reviews, and the company sending me the gear can't be happy wiht that because it looks awkward for them to publicise the review etc if it shows their competitors. But that is official review policy stated on my website, they either take it or leave it.