The evasive ingredient list

Ingredient reading was never easy, especially when you want to get past all the cover-ups companies do to hide tricky ingredients from consumers. However, it is a necessary skill for vegans and vegetarians alike to acquire, and is useful for non-veg consumers as well. In this aspect, you have to do your own homework.

"Dairy-free" and "non-dairy"
is not "vegan". Remember non-dairy creamer - which ironically, contains sodium caseinate. Many items on the market touted as dairy-free, are usually there to cater for those with allergies or intolerant to milk products, not to vegans. As such they can still contain other animal products or derivatives of them inside.

Vitamin D
could refer to vitamin D3 or D2 - D3 is derived from sheep's wool. They can call it using it's other name - cholecalciferol.

E-numbers
are great to hide disgusting ingredients such as crushed beetle food colouring, in case you like to know - this is called innocently as "E120" on the ingredient list. E120 can be found in anything that has red colouring - from your tomato sauce to your red candies. There are also a lot of other E-numbers that may not be vegan or vegetarian.

Pills
are things we can't do away with when we are sick. But try your best to avoid them because they are likely to be non-vegan, besides the issue of testing on animals. What many pills contain in their colour coating is lactose monohydrate. This is no doubt, derived from milk, and it is made with calf rennet as well (just like non-veg cheese). You won't find it in most of the patient information leaflet that comes with the pill, unless it is used in the pill-mix itself, because it is hidden in the colouring called "Opadry". It could also be hidden in other excipients as well.

Natural flavour
is another way to hide in animal ingredients without your knowing. I once bought a biscuit that taste distinctly of milk, but does not have milk or its derivatives in the ingredient list. But right at the end, it says "natural flavour" or it could be just "flavour". This is propriety information to the company, but at the same time, it could include stuff like dairy or even animal products. Recently, you may have heard that Jamie Oliver said that the castoreum from beaver anal gland is used in vanilla flavouring. This is also labelled as "natural flavouring".

"No added X"

does not ALWAYS mean that the product does not contain X. It means they do not add in, but it could be generated as part of the manufacturing process for one of the ingredients - think "hydrolyzed vegetable protein" and "MSG". It could also be found naturally in food such as tomatoes. This is not much of a "vegan" or "not vegan", but it's good to take note when it comes to things like sugar, MSG, salt.

The vegetarian resource group has a great website with additional things to look out for when reading labels.
You can also check out the Food addictives and E-numbers on this site.