Roast defects vvvvv


I have noticed that my really good roasts taste the same in a travel mug as they do in a regular mug. Some roasts though taste pretty good in a regular mug, but then awful in a travel mug. I am thinking there must be a roast defect happening here that is masked by drinking from a regular mug, but can’t figure out what. Under and overdeveloped are noticeable either way, so I don’t think it’s that. Maybe a sign of baked? Anyone else have this experience?