The most important thing I think someone needs to know before looking for a career coach is that they are honestly ready to make a change.
This doesn't necessarily mean a change of job. It may simply be a willingness to change how they operate in their current job or a willingness to change in how they think about their life.
This usually means some discomfort, a lot of honesty, and a bit of effort is required to navigate this change. Not everyone is up for that.
So if you're more comfortable describing the problems and doing nothing to rectifying them, then save your money. You don't need coach, you'd do just as well with a sympathetic hairdresser, bartender, or friend. :)