Usually if you are in the role it is fairly easy to detect change so i will not comment on that, however, at the interviewing stage, this is something that as consultants you have to learn to gauge quickly.
People need to remember that interviewing is a two way street (in fact if i am interviewing for a new staff member, a person who doesn't ask questions of me gets disregarded as a candidate due to not being able to come up with questions on the fly and be able to articulate these in an appropriate manner).
Ask questions of the management such as what changes have happened during the last 12 months, and listen to their response. then ask questions about roadblocks and how these were overcome, I find that, that sort of questioning goes a long way to giving me a gauge on how the company manages change and how resistent they could be.