It's been a long time. Hope this new thread finds you all well.
Anyway, I'd like to ask if I am correct in assuming that 'to dog mouth somebody' means the same as 'to mouth off...'.
I'm not familiar with the phrase but I would probably assume it meant the same as "to bad-mouth someone".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.