Stop being so reasonable and enlightening, that’s obviously not wanted around here.

Sure, but you're making the assumption that your beans are shiny because of butter, while we know all dark-roasted beans will be similarly shiny regardless. You're not providing any clear evidence that butter-roasted beans retain any oils from butter, and frankly I'm very skeptical of that being the case. Have you ever tried heating butter to 300C in a pan? (Do not actually try this, you will start an oil fire and create lots of smoke)

Since you're so tied up with not believing something:

  > Put beans roasted in butter next to beans not roasted in butter.

Spoiler: they look very different