I'd agree with the previous posts - I vape low power, higher Ohm and stronger liquid and if I use a clear drip tip I'll still get an effect like that - I just screw up a piece of tissue and twist it down the tip from time to time to clear it.
Real spit back is when you take a draw and you hear a pop or a bang and you get hot liquid in your mouth and I've only had it with the very odd faulty drop in coil.