I've had demands from Colorado, Washington and Oregon to pay taxes in those states for offices and employees that don't exist.
As an investment broker, we had a single client in Vermont and their regulator wanted us to pay $500 per year to be licensed in the state. I told him that the client moved there, we didn't solicit business in their state and every other state offers an exemption for a number of clients that do that to avoid paying the fee (we generated maybe $150 in commissions from her in a year). They said they would look into it. Oddly the exact same day we received a fax from the regulator wanting a campaign donation for the new position he was campaigning. We didn't make a donation and their determination was that we needed to be licensed.