I've experienced some similar irritations from CE-4 clearos and especially my Kanger T-3. I think the culprit (in my case) is a flooded atomizer which spits (sputters really) un-vaped juice up into my mouth. I've also noticed that there is usually a pretty loud crackling sound if I fire my mod (away from my mouth) and with the T3, I can actually see a little "fireworks-like" spray of e-juice shooting out of the drip tip. With my CE4s, I've found that loosening the screw-down driptip and tipping the apparatus slightly, releases the juice that builds up in the bottom of DT trapped by the white top of the atomizer region. The clearos tend to flood if they've been sitting on their sides (on the passenger seat in my car). I haven't found a fix for the T3 and have shelved it. If you notice a sweet taste (for fruity ecigs) on the tip of your tongue or lips, this may be what is happening.
If you're vaping PG-heavy juice, and you're getting some of the actual liquid on the tissues in your mouth/throat, well PG is hygroscopic, meaning that it will pull water out of those tissues and dry them severely, which would probably dry and then irritate the ever-loving heck out of them. (not an MD, but a chemist)
Thou shalt drink water while vaping is like one of the ten commandments of vaping I've learned, up there with Thou shouldest always have backup and Thou shall NEVER take the name of ProVari in vain
Seriously though, you might want to check out a Kanger Mini-Tank or other bottom coil rig (T3 not recommended though).
I think you may be right about the cheap equipment being responsible for getting a bit of juice in my mouth. I am waiting for a Provari, a carto tank, and a Kanger Protank in the mail, so that may solve everything.