Barking rather than a nice hello

[helenb14]

I would say that generally Seve has been quite a placid dog, but he has recently started barking when approached, not everyone, and doesn't have a pattern, some dog owners who are careful with their approach, children I can understand as they are bouncy and unpredictable.
I know he doesn't like the top of his head being touched by strangers and always say just let him sniff you first, but I'd be grateful for some advice now, as I've had a few comments of 'snappy dog' and I've never thought of him in this way.

[MaggieR]

Have to be honest and say I wouldn't expect him to have to greet everyone... Maggie's the same, some people she's fine with and goes to greet them, some she's a little reticent with, and others she will just bark at. For whatever reason... I never make her greet anybody she doesn't want to, if she's offlead, which she is most of the time I call her to me. If she's onlead I just lead her away and say sorry she's a bit nervous of people she doesn't know. 
Its a bit like people I guess, we don't like everyone we meet either for whatever reason
Might not be the best way, but works for me.