To put it briefly, where there's smoke, there's fire. There are factors that seem to exist, things like tax advisers who charge contingent fees. Who would do that? That is, it's contingent on the tax benefit. So that's one hallmark.
Contractual protection, that is a guarantee. “Even if this transaction doesn't work, the CRA challenges it, don't worry, we will guarantee you your tax benefit, we'll pay it for you.” That is the second one.
Another is confidential protection. “You're not allowed to disclose the details of this to anybody.”
Two out of three, and now you have to report.