SMs will reduce the yield of any plant, but if the flowering is almost over the plant is already dying. They don't eat THC or flowers, just the juicy green plant.
As for smelling bad, IMHO all smoking smells bad.
I don't like the taste of beer or wine either.
But it's a process you go through to achieve the end result, altered mood/consciousness.
My last grow had spider mites in the final 2-3 weeks, I didn't do anything.
Still got some left and it's fine.
This year it's been too wet/humid, and spider mites like it dry, so I have none so far.