Mouse test: Run all relevant self-tests for 'laser mouse'.
If 'clean'; depress left button, and move hand describing a series of on-screen B's. Check only with the upper case letter 'B' or the test will result in an automatic 'Fail'.
Lift finger from left button.
Wait ten seconds.
Lift mouse from mouse pad, and check to see if the mouse laser left a trail of letter B's anywhere on the pad. Even partial B's matter, so use a good light source and be as thorough as possible.
If no B's are found; Congratulations; your mouse is free from Ray-B's!