I've never put more new plugs in mine since i got it! I think they only die cos they get wet easy if it doesnt fire up straight away, i bet the old ones would of been ok but while it was in bits i thought what the hell, and i got them trade which helps!
I'll test them when i fire me bike up for the first time for a year when it gets a bit warmer, see if it still start on the button! Tho i never got the carbs drianed so i bet it'll have to come to bits first!

Cheers
Ian

When the bike is operating properly AND everything is maintained in good order you should never kill the plugs if correct starting technique is used.

I've fouled one set of plugs in my history of NC ownership, this was on a racebike with full hrc carb setup and using ngk race plugs (R847-10), I've never fouled any plugs on a street bike.

It seems to me that plug fouling is usually done by those newish to NC ownership - it can be an expensive lesson so one best learnt quickly!