Okay, here's my poor attempt to make a game... As the inspiration was low in the air, I was only able to get an idea from Panda's special game, "Guess who's wearing glasses"...
So, I'll give you are series with a certain number, and you must name that many characters from that series with glasses.
For example:
A Recipe for the Heart (7).
Answer: 1. Lydia Shum. 2. Jerry Lam. 3. Kwan Hoi San. 4. Wu Fung. 5. Annabelle Lau. 6. Law Mong. 7. Law Ka Ying.
Well, I don't post because it seems hard to think of how many people (coming up with the number) were wearing glasses in that series. I think I can picture an actor/actress wearing glasses even if they didn't. For example, you said Gilbert wears glasses in most of his series, so I could just picture him in glasses for each series, even if he didn't wear any for that series. In other words, if I'm used to seeing an actor/actress wearing glasses, then I would be unsure about it in other series.