You'd be happy to live opposite a house where every inch was covered with flashing Santa figures and reindeers then, Laguna? I would. It's not something I'd choose to do to my house but it's not adding to my electricity bill and certainly not the most offensive thing a neighbour could do to the outside of their house.
The old "it's for charity" chestnut is wheeled out every year - no it's bloody not. If you were serious about raising money for charity there are lots more cost effective ways to do it and which don't piss off your neighbours who have to contend with cars and pedestrians gawping... Having said that my children get endless fun at this time of year trying to see who can spot the naffest house when we're out in teh car
Are you seriously annoyed because they're raising money for charity in a way that you don't find particularly cost effective? If a charity gets £50 that they wouldn't have got otherwise, I suspect they'd be quite happy with that. Not everyone is a marathon runner.
And I'd totally understand about the cars and people staring, but when you and your children are in your car and they're on the lookout for houses with the 'naffest' lights on, how many areas have been congested with traffic around those houses? How many hordes of pedestrians have you seen getting in everyone's way? Or do most people tend to do the same thing as you and your family and just look at them as they drive past?
YANBU to find them tacky. Everyone's taste is different and it would be a very boring place if we all liked the same. YABU (and making yourself sound rather like Hyacinth Bucket) to think of things in terms of how 'common' things are.