Yes there was an episode where they showed Niles wife. You could only see her from the rear. You never saw her face. I do not remember what season this was or what episode it was either.
Season 11 Episode 22
In the episode Niles is standing at the buffet with Karl. Karl points to something and shows Niles how to eat it. Niles tries, but as soon as Karl turns his back he pulls it out and puts it back on the tray. When Karl turns around again, Niles nods appreciatively, then pulls out his handkerchief and wipes his tongue off, but it never explains what it was.
Episode 2.23 - The Innkeepers
season 5, episode 15: Room Service
Yes there was an episode where they showed Niles wife. You could only see her from the rear. You never saw her face. I do not remember what season this was or what episode it was either.
Season 11 Episode 22
In the episode Niles is standing at the buffet with Karl. Karl points to something and shows Niles how to eat it. Niles tries, but as soon as Karl turns his back he pulls it out and puts it back on the tray. When Karl turns around again, Niles nods appreciatively, then pulls out his handkerchief and wipes his tongue off, but it never explains what it was.
It was in more than one episode.
Episode 2.23 - The Innkeepers
season 5, episode 15: Room Service
yes
Are you sure it was Niles, or do you mean Martin when she was sick with the flu? If it is that one, than it is "Four For the Seesaw."
Season 4, Episode 22 "Are You Being Served"
Season 2 episode 16 - Canasta Masta
The Finale: Part 2
Season 6 Ep 14