I thought there was a bug report already for this, but I couldn't find it, so maybe it was buried in another thread somewhere.
If there is a vertical image in a marketplace thread, it gets squashed.
Example: https://pinside.com/pinball/forum/topic/for-sale-star-trek-the-next-generation-2
Screenshot: 2015-08-26 09_56_08-For sale_ Star Trek_ The Next Generation - Pinside.com.png
Actual image: https://img-s.pinside.com/market/aa/medium/aa5508bb9f08ed15c9cd95a9f181c0f95ca12c0c.jpg
aa5508bb9f08ed15c9cd95a9f181c0f95ca12c0c.jpg