Some products you might think were vegan but often aren't
(or, "what people I know have been most surprised to learn about food products")
Margarine - people seem to be surprised when I tell them that margarine isn't vegan, so it's gone at the top of the list. Yes, even the ones with pictures of olives and sunflowers on them. It's not vegan unless it says so on the tub.
Vitalite is not currently suitable for vegans (it's dairy-free but contains animal-derived vitamin D) but the manufacturers are working on a new recipe and plan to relaunch it as suitable for vegans in the near future (updated June 08).
Dark or plain chocolate - British chocolate manufacturers have an annoying habit of shoving milk into dark chocolate, sometimes it's even one of the main ingredients!
Quorn - just because it's meat-free doesn't mean it's vegan. All Quorn products contain eggs and are therefore unsuitable for vegans.
Many brands of 'veggie' burgers, sausages, etc. - a lot of vegetarian 'meat alternative' products contain eggs and milk.
Fresh chopped herbs/spices in squeezy plastic tubes - some of them contain whey powder. Yes, they can even make herbs be not suitable for vegans.
Worcestershire sauce - contains fish. You can get vegetarian Worcestershire sauce, or if you're anywhere near Sheffield, try Henderson's Relish instead.
Honey - it's an animal product, so vegans don't eat it. The main place to watch out for honey on the ingredients list is in breakfast cereal, as many of them use it as a sweetner.
Some beers and wines - yep, Guinness isn't suitable for vegans... Some beers, particularly real ales, are filtered with fish swim bladders to make the sediment clear faster. Egg, blood and bone marrow, among other things, are often used to filter wines.
Crisps - don't ask me why the feel the need to put milk powder into salt and pepper-flavoured crisps, but sometimes they do, so be aware. Apparently they use lactose to hold the flavour, or something like that. Still annoying though.
Chewy sweets and marshmallows - many of these contain gelatine and aren't suitable for vegetarians or vegans.