What flavor are you vaping? This can have a lot to do with burnt taste, my experience has been that darker blends (such as coffee/vanilla or a blend of the two) will cause the coils to need cleaning more than the clear flavors. Changing the flavor wick on top (if present) regularly helps. I prefer to use the silica wick scraps from coil rebuilding for this purpose, no wasted material.
In fact, I've had one clear flavor (Relax Pina Colada from Vapor Beast) that's been topped off several times, almost half of the 30ml bottle & have yet not had to rinse/change the coil. Though I did replace the flavor wick once, as the stock ones are made of the cheap stuff.
As for cleaning the coils, if they've not burned out, I remove them & allow hot tap water from the bathroom sink to trickle over them for 4-5 minutes. Then dry as much as possible with a paper towel, afterwards place the coil on a small box beside of my main laptop with the coil facing the exhaust vent. The warm, sometimes hot, air will dry these much faster than just turning them upside down.
When I reuse that coil, I always do so with the same or very close flavor. Usually they don't last as long as when new, but any added life is better than none. Too, the reused coil doesn't need to be broken in, new ones (or rebuilt) takes a bit to vape really good.
Also, I aim for 2.3-2.5 ohms, seems like the 1.8 ohm ones runs hotter by nature.
Cat