I think that vegans also fail to distinguish their arguments and bombard people with all of them. They need to find which argument works on whichever person, and address only that aspect.
So, for example, (a) most people in the west, which is the biggest meat consumer, accept and are worried about global warming. If you can show evidence that a large proportion of it is due to cow flatulence and deforestation, you can make an argument for reducing consumption of burgers, for example.
The other arguments are (whether true or not): (b) it's morally wrong to kill any sentient being, (c) mass farmed animals are full of hormones/antibiotics/BSE/whatever, (d) meat is actually not healthy for you (e) we're not biologically 'designed' to eat meat.
So for example, I only find (a) to (c) compelling; (d) and (e) don't really persuade me, because of palaeontological evidence that humans have been doing it for 1.6 million years - ie from a time BEFORE we were actually modern humans (which is only in the last 100-200 000 years or so - I can't recall the exact timeframe).
Moreover, even (c) isn't that compelling if you go for free-range meats or venison. From my point of view, the moral argument is the strongest. The bigger the frontal cortex, the more it can suffer, the less you should consider eating it.
Lastly, as for raw food vegans: Processing isn't inherently bad. I mean think about it. If you put aside preservatives, colourants and flavour enhancers, you're left with "processing" which usually means "liquidising and mixing". How is that any different from what your teeth do?