The common tasting glass has a bowl that narrows at the rim.
The aromas are concentrated inside the glass and better appreciated.
Dust, dirt or residue of soap spoil wine.
The best way to clean glasses is to dishwash them!
Hand wash: bottle brush, dish soap, polishing cloth microfiber polishing cloth erases smudges more easily than a cotton kitchen towel and won't leave lint behind. Hot water for tough spots.