On the OKC trade, I think Adams is actually a highly valued player by NBA front offices, even with his sizeable contract. JR right now is a net negative as an asset given his contract, although he may have some value as an expiring when the trade deadline comes around. Clarkson is a guy who shows potential, but after a decent amount of time in the league, I'm not too hopeful that he turns into much more than what we're seeing now. With his contract, he might be viewed as a net negative or a very marginal positive.
On the Denver trade, yes, Sexton has decent trade value based on upside, but that is mitigated somewhat by the fact that he hasn't proven anything yet. He could flop. I would be shocked if he did, but it is at least possible at this point. Gary Harris and Jamal Murray have already shown that they can at least hang in the league as productive players, with neither one of them reaching their peak yet, so both of them have pretty decent trade value right now.
Tristan Thompson's trade value is probably a polarizing topic with this board from what I've read. I think his trade value is slightly positive since he only has two years left and could show this year that he's in better shape, healthy, and looking like TT of 2015. Others might argue that he'll never be back in 2015 form, and he was a limited offensive player even at that time anyway (which I wouldn't argue on the last point either). In that case, his contract makes him a net negative asset.