I have sometimes switched to "do the job I would stay for" mode, but it's a fine line between that and "burn bridges" mode. In the end it hasn't worked out; things kept going downhill, though it did help confirm my feeling and improve my day to day a little.
So I'd say trust your instincts — if it seems bad and you've raised concerns and have a way out, take it. The caveat there is to always be on the lookout for better options / do the occasional interview, since you won't have as high a bar once you absolutely have to get out.