Are faculty salaries negotiable in general? Wherever they are negotiable, how could applicants gain insights about the statistics of offers or the extent of safe negotiation?
This answer applies to Canada.
There is generally a fixed pay scale in Canada. But you can always try to negotiate and sometimes it works. Especially, if someone moves from a faculty position to another university and the salary would be lower, then that person should negotiate to keep at least the same salary (the salary should not decrease). Besides, some top level professors may negotiate to get application for a research chair or that the university also hire their husband/spouse at the same university. This has been done in some cases. You can also negotiate to try to get a permanent position, etc.