Many are dipped in honey. In the UK they often don't mention this on the label. Some bakers grease the tins with animal fat. If you're using a local bakery ask them what they grease their tins with. Be careful though, the almond-raisin variety contains animal based glycerin.
Many manufacturers use whey as the flavour carrier.
Check with your local vegan society as to what crisps are vegan. If a manufacturer can stick some part of an animal in something, chances are they probably will. Learn to be a fastidious label reader and avoid products not properly labelled unless you know for sure that they are suitable for vegans. Buy products from companies who make their stance on animal products known. Look out for ethically vegan companies and support them when possible.