Having an advisory role is similar, if not more important, to making a financial investment, thus the same VC investment standard due diligence is necessary. After all, an adviser will be investing his/hers time, which is his/hers most valuable asset. One can always make more money, but can't really buy more time.
I have seen VCs that would ask for much more equity if the investment deal was not just about money. That speaks volumes of how much they value their time.
I am talking about the real thing and not just a standard meeting once a month for reporting purposes.