Cat smells bad from his face end, it smells of faeces to me! Could it be something more serious than his teeth, can't get him an appt until Wed I wondered if he really needs to seen more urgently than that.
He eats 99% of the time dried food - royal cannin, with the very occasional stolen treat of tuna, chicken, licking out the tin of tomatoes etc.
Should his mouth look very pink or does that depend on colouring, he is fawn silver and his lips look pale to me but that could be normal.