What a magnificent contrast. You have an actual swimsuit that is colored to be invisible. Then you have a suit that is colored realistically enough but is just painted on.
Hmmm... If you actually look at it, not just glance at it, the thumbnail isn't that misleading. Applying Blue Bunny logic, if something looks like a nipple, it IS a nipple, so Sanae's probably body-painted and naked. The fact that the entirety of Reimu's swimsuit area is tan (no pink) means there are no nipples, and Ao Usagi would never pass up the chance to draw a boob. Therefore, Reimu is probably wearing SOMETHING.