Which foods are most likely contaminated by dairy due to processing methods used? I am Vegan but also highly allergic to milk and wondered if anyone is familiar, or has come across any knowledge about which foods and food groups are typically processed in a factory which also handles dairy, other than the obvious like milk, cheese and products labelled with dairy. 

So for example, a lot of different chips/crisps have been exposed to dairy as have dark chocolates even though these products don't always have dairy in their recipes. 

I am essentially, trying to eliminate dairy from my diet but sometimes products inadvertently are contaminated with diary by the lines they are produced on etc.
Practices will differ with country (or community in some cases) of origin. A country where few dairy products are commonly consumed or produced, or where a significant amount of the population is not dairy tolerant (parts of asia) or where religious codex exists about dairy use (eg jewish communities) is likely to have different practices from scandinavian countries that lead the world in per-capita dairy consumption.

Equally, the country where the product is marketed/consumed is important, especially when it comes to what has to be declared on the label, with which tolerance levels, by whom. Also try to take advantage of multi-language, multi-market label text - sometimes important hints are found only in foreign language versions of ingredient lists or allergy advice (ever noticed that they sometimes differ - where it is unlikely that two different products are described)....