It's harder to smell it when they're frozen, but as they thaw (& you mentioned the tails were thawed, which makes sense, ya?) you'll notice the smell more, and if
like others mentioned, you "blow-dry them before feeding" you'll get the very "best" aroma, lol. It's normal rat B.O. & stronger from male rats than females but in
a bag of feeders it's just gonna be there. As I said before, ppl with PET rats sometimes BATHE them for this very reason! -they do tend to smell like RATS.
And the bigger (older) the rats were in life, the more body odor they produce...it's perfume to other ratties, you know. Not so much to us, though...
You never want your feeders to thaw, but since these were minimally thawed & still cold, as I said before, I think you're fine to re-freeze & feed them. If your snakes
say otherwise, then maybe your nose has missed something that theirs got. Obviously, this isn't a "scratch & sniff" forum, lol. You should already have been familiar
with their normal aroma from prior feeds? (and if you're worried that the tails thawed & could have spoiled, you could remove & toss them...your snake won't care.)
P.S. I still don't recommend re-freezing any that are TOTALLY thawed (as in "re-offering" prey that was warmed & then refused...that's asking for trouble)
But from what you described, I believe these are SAFE to feed. OK?