Yeah carbs seem to be the one that everyone always forgets about! I've had people tell me they probably consume less sugar than me while they have been eating a huge plate of pasta or then go and drink a pint of fruit juice :S.
Sugar obviously has a big effect on me because I hardly have it, but when I do it makes me feel grumpy, thirsty, wired up and I get a headache.
People say drinking soda (non diet) makes your more thirsty but I'm inclined to believe that it's because your sugar levels dip and your body craves more.
I think it's fine to have sweets in moderation, I do (mainly because diabetic sweets taste like crap) but I hate that almost everything you buy in supermarkets is packed with sugars or sweeteners, it's like there is no escape!