I think it depends on the tribe and how protective they tend to be. My overall impression in working with tribes is that if one is fair and straightforward with them, they tend to reciprocate.
I will agree to that, to an extent. When involved contractually on a larger scale, I too, have never experienced a problem. When dealing with buying and selling livestock, vehicles, things valued at less than $20,000, I have had problems.
The access granted at my area reservations (Crow, N. Cheyenne, Lakota, Arapahoe, Shoshone) for settling rez/off-rez disputes is getting better, but can take a lot of time. My kids are part Lakota, but not being active on the rez it doesn't help me at all.