I've built several bows with clear glass and so far (knock on wood), I havn't had any spots show up.
After I started hearing the reports of this I quite using clear glass.
I'm going to try it on one more bow (when I built the one with the Flaming Ambrosia Maple).
If I get any spot or streaks it will be my last clear glass bow.
Besides, clear glass is much higher in cost the the colors.
Troy