If you take birth control pills, or just about any pill for that matter, there's a lactose binder.
If you develop photos, I believe gelatin is still used in the processing.
If you ever drive a car, you're going to splatter a few bugs on your windshield. Heck, even riding my bike I'll get a few bugs splattering on my face or even in my mouth. It happens.
As a doctor, I treat patients with heparin, which is pork-derived. It is often the best option medically for them.
Please know I'm not *that* lax. I went out Tuesday night to an Italian restaurant. I ordered a mushroom pizza without cheese, said please make sure there's no butter at all on this. And for dessert had some sorbet. At the end of the meal, I was sure to thank our waiter plentifully for taking care of my vegan needs. I didn't annoy my waiter or my friends I was eating with, kept it simple.
Did the dough conditioner have mono-diglycerides derived from an animal? How about the source of the lecithin for the bread -- soy or animal? Was there some honey in the crust? Was the pizza prepared on the same surface as animal products, and was there possibly cross-contamination? Don't know. What's important to me is that by avoiding the dairy in the pizza that I didn't contribute to the suffering of dairy and veal cows.
To the person who posted that she only eats at vegan restaurants, I wish I could do that. But I live in Boston, with a limited supply of veg/vegan restaurants and a vast majority of friends who do consume meat. Every so often I can take them out to Grasshopper or Buddha's Delight (two vegan restaurants), but not every time.
To me, it's all about the big picture. It's nearly impossible to be perfect.