I normally clean out all components I receive, that means taking them apart and doing a wipe down including all of the internal parts. It sounds like your problem is a bad batch of atomizers, the burnt taste could be partially shorting wires ... make sure the E-Liquid has not turned and has been stored properly.
I suggest you look up a rebuild tutorial for those coils and see where that takes you. If everything is clean and new, you shouldnt be having this problem and if you have a local vape shop maybe they will have more insight/refund "if you bought local?" what seems to be a defective batch.
Gurgling is a *feature* of evod/to-go tanks and many bottom coil components, the best way to alleviate it is to take toilet paper, cover the drip tip and while firmly holding the tank shaking it briskly and at the end wiping the tip out cleanly. There is no PERFECT fix for it and unless the manufacturers get smart and redesign these clearomizers. If you dont want to rebuild coils or are still unable to fix the problem I would petition Aspire directly for support, they might appreciate being sent a batch of what appears to be faulty coils for review.