Generally, accent stuff doesn't bother me, but god it grates me when Britain is generalised into London, and then london is only cockneys and lords (which are two of the smallest percentages of the population & accents). Especially in one interview with the makers of CSI who, when asked if he wanted to do a CSI in england, said "Yeah, i love the city, with its big..whats it..eye and stuff". God it annoys me.
A little off topic, but...basically, usually it doesnt but occassionally it really really annoys me.