Interior condensation
Water beading on the inside of the glass toward the room usually means warm moist air hitting cold glass.
Run bath fans, use a dehumidifier, and check that curtains are not trapping air against the pane.
Between the panes
Fog or mineral haze trapped between double-pane units means the seal failed. Wiping the inside will not fix it.
Replacement inserts or full frame units depend on frame condition and whether you are already doing siding.
Pair with siding when it makes sense
Opening the wall once for siding lets us set proper flashing and foam at the rough opening — not just swap glass.
We will not push full-frame replacement when a sound insert solves the problem.