Is hormone testing really acurrate?

My doctor and obgyn says hormone testing is inaccurate b/c women's hormones change so frequently. It's also very costly. But I still see lots of posts with women posting their hormone levels from tests. If it's so inaccurate, why are so many ppl getting it done? Are their docs just trying to get money?
I wish I could have mine tested due to my strange (to me) weight gain, my weird early AM sweats, and (least importantly) my low desire (tho that could be my meds). I'm not sure what to do.