Yvonne,

First, you need to know that yes, there is a very good chance of polygraph results being inaccurate. The only ones claiming that polygraph testing is highly accurate are the polygraph operators themselves. The consensus view among scientists is that polygraph testing has no scientific basis whatsoever. See, for example, Professor William G. Iacono's article, "Forensic 'Lie Detection': Procedures Without Scientific Basis":

http://antipolygraph.org/articles/article-018.shtml

The questions about playing with one's penis, watching pornography, and getting excited by it were "control" questions that are expected to provoke a physiological response. If your husband had reacted more strongly to such questions than to the relevant questions (about adultery), he would have passed. That he failed indicates only that he reacted more strongly to the relevant questions, not that he is lying.

It is not unusual for a falsely accused person to react more strongly when truthfully answering an accusatory relevant question about an issue of great importance than when answering a "control" question.

Note that had your husband been a liar intent on beating the polygraph, he could have easily learned how to do so. AntiPolygraph.org provides detailed information on how to pass a polygraph in our free e-book, The Lie Behind the Lie Detector:

https://antipolygraph.org/lie-behind-the-lie-detector.pdf

We provide this information in order to give honest people the means to protect themselves against the risk of a false positive outcome, but this same information can also be used by liars to pass.

I think that you should accord the polygraph results no weight at all, as they are, in fact, evidence of nothing. Relying on unreliable polygraph chart readings is foolhardy and may well lead to needless harm. See the following public statement by Gary Smith for an example of such harm:

https://antipolygraph.org/statements/statement-028.pdf

Regarding polygraph operator Ted Todd, the following message thread may be of interest:

https://antipolygraph.org/cgi-bin/forums/YaBB.pl?board=Policy;action=display;num=1066295284