See . . . . . that's the thing. The collie, Twig, is soft, she is a sweet little dog, with the kind of temperament that I know if she was physically corrected, it would do huge damage. A raised tone is all that is needed, and now I have done a lot of training (and had some help) thats rarely even needed.
However, the dogs I have physically corrected. . . . . . are two running dogs and a hound/terrier.
Two had a slap, after they pulled down sheep, working a gorse banking on a hill, flushing and killing foxes, and they flushed a raggedy old coloured ewe from the gorse, couldn't really see her over the cover and gave chase, their blood was up when they got to her and had her pinned down when I got there (quickly). They knew very much that it was wrong, but in the context, and their youth and the heat of the moment they though 'to hell with it'. They did not damage the ewe, but held her down. I got there, gave both a hard slap and pinned them to the ground by their throats. . . . . and from that day forth they never ever touched one, despite the same scenario playing out many times!
The third, is a young lurcher bitch (bull/collie/saluki/grey/whippet) who is incredibly loyal, a very much one man dog, and extremely protective / jealous over me. I was giving the mrs a lot of attention after being away from home for a while and had stupidly not given the dog her fair share when I got in. . . . . . .she decided to snarl, and then snap at the mrs. Needless to say she got a sharp tap on the nose, and a stern telling off.
I feel that I know my dogs, and generally deal with very high drive, very full on dogs, which I expect to kill things on a weekly (sometimes daily basis), as such I expect extreme obedience in certain areas. . . . . . and occasionally will need to use a physical reprimand to achieve this. Mind you i'm talking a slap, not a beating, and it probably happens once or twice in a dogs life at most.
However, I have never EVER struck, slapped, hit or tapped a collie. . . . . . and don't feel I would ever need to. Different dogs, have different hearts and heads, and as a good trainer you need to be able to see inside those two things and make a good judgement call.
I'd say 90% of dog owners can't train a dog properly.