Odd Question

Would it be frowned upon to be a member of one association but actually follow the standards of a different one? For whatever reasons, I would like to join InterNACHI but follow, and advertise, the CAHPI standards. What do you think?

Many do belong to more then one association.
I at one time belonged to three at the same time .
Now just belong to the best one .

In being a member of InterNACHI and CAHPI I am sure that you are agreeing to follow each of these organizations standards of practice.
In doing so your safe bet would be to hi-bred the two to ensure you cover the basics of both.