In my experience (for what it is worth)

When exercising always purple.

Other times it might be light pink, but I always chalk it up to lots of water drinking.

I would think that if you tested just after a meal that you run the risk of being in the beige just because the carbs you eat (even if limited) are being burned, a test 2 hours later may find that body fat is being burned thus changing the color back to pink.

Do they really recommend you test so often?

I only test when my weight loss has slowed or I think I may have over done the carbs by accident while dining out or just not carefully counting.