Recurring characters, good and bad

The distiction is simple, the bad recurring characters are the ones in modern sketch shows that over use them, and reuse the same jokes over and over and over again. Examples of these include the RAF men on Armstrong and Miller and Cathrine Tate's characters. Now the good ones are the ones out of 80's and 90's sketch shows, tough I can't put the reason as to why into words. Examples of these include Siadwell off of Naked Video and the head to head monolouges from Alas Smith and Jones. What do you have to say on the subject?

I'd say the RAF men are good recurring characters. :)