You can be rigorous without being toxic or--sadly--toxic without being rigorous. In fact, I'd say they are almost unrelated and the same critique can be leveled either way.
I don't think @jltsiren meant that you have to have unconditional trust in someone else's work. Instead, you should approach it with a bit of humility. At a talk, the speaker is usually presenting work they've spent years on, whereas most of the audience saw it for the first time fifteen minutes ago. In most cases, you can trust that they've thought a bit about the obvious, show-stopping objection that immediately popped into your head.
You can--and should--verify this assumption too, but there are light-years between:
- "Could you walk us through your experiment design again? In particular, is there a wash-out period to account for any potential carryover effects?"
- "These results are hot garbage. I don't trust any fMRI stuff and as for the rest, I can't believe you'd run a crossover experiment for this because there are obviously carryover effects that you've glossed over in your talk."