Opinions on Baby dopplers

As someone who works in the medical field I despise these things when people buy at home dopplers.....
We have woman hysterical at least every other day because they have one and were able to hear the baby's heart beat yesterday and not today....so we have to rush them in and show them their baby is still alive...
Baby's move all the time and depending on the position you may or may not hear that heart beat.... If you don't hear it you will freak out.
I understand people just wanting the extra reassurance between appointments but honestly from my experience they've caused more stress than they have anything else... 
If you have one then the temptation to listen is always there and you won't always be able to hear it and that causes stress and panic... Those dopplers are not as good as the ones we have here at the hospital... 
Obviously id never tell someone what to do its your life to live but this is my honest opinion on at home dopplers.