1st of all, drone cells can be seen in abundance, while queen cells.... if you see 5 or 6 cells of a kind on one frame, they're probably queen cells.
anyway...it's almost impossible to mix them up, just do a search on google for both, look at them and that's it.
so far i haven't seen a QC that wasn't pointing downwards, what your friend probably actually meant is, that they are not necessarily started at the bottom of a frame, that way, they start as normal WC but get prolonged and downward pointed. this happenes in cases of suprecession or emergency queen raising.
still...swarm prevention is not really succesfull if they make QC as swarm cells so...your point is to never see them ;) well, not never, just...not in a swarm manner.