SMEs do not criticize their colleagues or dismiss what they say, especially not in front of customers. SMEs should be agents of unity, not division. They should constantly seek opportunities to agree. When you do agree, acknowledge it, point it out, emphasize it, and celebrate it.
We live in a time of hypercriticism. Politicians, pundits, and professionals of many disciplines have demonstrated that contests can be won through cutting criticism. Don’t buy into it. Finding fault with your colleagues doesn't help you and it doesn’t help them. Even when you’re right, criticism hurts them and soils you. Don’t do it.