The glass is...

[Slev]

I had a glass of  a nice full bodied red wine tonight.  Finished it,  and then got a bottle of Kinsale ipa (rocket ship).  Out of laziness I used the same glass,  but didn't rinse.  (was watching a movie and had drained the glass pretty well!)
But got a taste that I would describe as metallic.  Kinda coated my mouth.  (I find that particular ipa to be a pleasant, almost sweet taste usually).  I finished the glass,  thinking the metallic taste odd,  but the second glass was similar. Unpleasant.  So I got a new glass and it tasted as I expected.  Was surprised that the taste was so affected by what must have been the residue of the wine,  even after a second fill. Just goes to show the importance or a freah/clean glass