I have acertained that the "bad taste" is from epithelial cells shedding from tongue and cheeks, which degranulate nitrite containing molecules. This buids on tongue very quickly, in non-oxygenated environment--as in sleep state. This also activates certain bacteria which contribute to build-up, and can also cause "geographic tongue". The patches are caused by nitric acid burns. Do you have occassional heart palpatations? Shroom