Then enlighten us to how it works Sledge. You only know how something does by having a knowledge of how it does work. If you do not have that intricate knowledge, then your opinion is not valid.
The GSR is an indirect measure of one aspect of
autonomic arousal. This is influenced by all kinds of stuff (see link). The reason polygraphs measure more than one response type, and require extended work by experienced operators to establish baseline responses, is because it is extremely hard to isolate any particular cause of autonomic arousal, let alone its relationship to the subject's state of mind at any particular time. Pretty much the best they can do is to assume that temporary broad AN arousal is due to (possibly sub or pre-conscious) anxiety, based on a previously established response pattern in that individual. Over an extended period, they then hope to correlate the assumed anxiety responses with the questions asked, based on the results obtained when establishing the baseline responses to previous true/false answers. If it works at all, it's more an art than a science.
Excitement, tiredness, temperature change, a yawn, a sigh, a random thought, physical movement, muscle relaxation, muscle tension, various sounds, a cigarette, lack of a cigarette, coffee or tea, a full bladder, even digestive disturbance can affect AN arousal. GSR response alone is even more labile. I know this from experience, having done a thesis on the peripheral vasoconstrictive response to noise.