I the guy your looking for. I have been doing microscopic work for several years now, using a Carl Seiss photomic 2 with modern objectives and using a Coolpix 990 digital camera [until I can afford better CAMERA equipment}.
I have made errors in the past as well due to artifacts, but sometimes I mistake important things as artifacts as well.
I try and make damn sure I lable the object correctly, esp. where parasitic single-celled animals are concerned.
Something like fluke, or pinworm etc. is a no brainer----------------Shroom