So if I was charged with a crime and when offered a polygraph test and I refused it on the grounds that it is unreliable I would be treated as being likely to be "disingenuous" and therefore presumably more likely to be guilty?

Edit: I meant more likely to be thought of as guilty.

Except that in this case the defendant should have a defense attorney who will tell them the truth, that the ordeal itself is a farce and the real test is whether agreeing to suffer it will convince the prosecutor.

Which destroys its value as a filter and converts it back into its true form, a waste of tax dollars on pseudoscience BS. (And a method for prosecutors to coerce innocent defendants into giving up their right to remain silent or communicate through their attorney.)