Been playing for years, LR1 on two platforms and I still do this every time there's a Nekros in the squad. I'm pretty sure Nekros' "raised dead" are affected by his energy or emissions colours. Revenant's thralls have a marker over their heads, but it can be hard to spot in the heat of the battle.
I agree with you - it would be nice if this were more obvious somehow, but even then you'd still get people (myself included) not paying attention.