Bonjour à tous !
This is such an interesting conversation, and indeed a tricky point of vocabulary :)
First, I do agree that the US "bummed" here has more of a "I'm feeling down, deflated" meaning, unlike its pretty rude UK equivalent (look it up!) ;)
However, it's worth noting that "dégoûté" in French also has the meaning of "being gutted (UK), very disappointed, fed up" with a situation. In modern colloquial French, I'd even say it's its main meaning:
-> Le concert a été annulé, je suis trop dégoûté(e) ! or its common abbreviation Je suis trop dèg! [daigg]
As for "snookered" (which I had to look up), it's more to do with "feeling had, taken advantage of", again not quite the right nuance.
So here we definitely have an issue of not matching quite the feeling between FR and EN. I would definitely use "gutted" myself, but can't quite come up with a US equivalent, so I decided to change the question and simply include a hint to avoid any ambiguity :)
I hope that's helpful, and thank you very much for this interesting chat!
Bonne journée !