Scantrons use special technology to read the marks you make. The technology isn't sensitive to things like lip gloss or chapstick.
The only thing that will affect your Scantron answers is if your marks are:
* Not dark enough: Make sure to fill in the bubbles completely and firmly.
* Outside the bubble: Keep your markings inside the designated areas.
* Too close together: Leave a bit of space between your marks.
So, feel free to apply your lip gloss or chapstick without worrying about it affecting your Scantron answers. Focus on filling out the bubbles accurately and you'll be good to go!