Good point about alignment and drafts. When we had our windows replaced a couple years back, I noticed condensation too, even though everything looked perfectly level. Turns out the installers had missed sealing a tiny gap at the top corner—barely noticeable, but enough to let cold air sneak in and cause moisture buildup.
Your incense stick trick is spot-on, by the way. I used a candle flame myself (didn't have incense handy, haha), and sure enough, it flickered near that corner. After sealing it up properly, the condensation issue pretty much disappeared. Alignment matters, but sometimes it's those sneaky little gaps that cause the real trouble.
I'd definitely recommend double-checking around all edges carefully—sometimes installers rush a bit toward the end of the day. Better safe than sorry...and dry windows are worth the extra effort.
Good catch on the sealing issue—it's crazy how much difference those tiny gaps make. I've seen people obsess over window brands and insulation ratings but totally overlook proper sealing. Curious if anyone's tried thermal imaging cameras to pinpoint leaks? Borrowed one from a friend last winter, and it was eye-opening...makes incense sticks and candles seem old-school, haha.