Not sure about burnt bridges
I actually "reneged" on two job offers. The first time it was because I did not feel comfortable accepting a one-year contract. I was frank with the hiring manager at the time. When, after being laid off, I came knocking back, eight years later, the same hiring manager gave me a permanent job.
The second time, was because I was interviewed and offered a job by a VP. When I met my supervisor, a week after my acceptance but before my official start date, I realized I would have a hard time working with that person. I submitted my "resignation." Within a year, that company was bankrupt.
Sometimes changing your mind is not a bad thing.
