Good dubs do exist but i really do just prefer the japanese voice actors most of the time and the dub in a lot of cases just doesn't come close. I do give it a go to see what its like because sometimes i find good ones.

Cowboy bebop is and always will have the most immaculate dub out there. But most dubs lets be honest just sound like pokemon and totally ruin whatever emotion was supposed to be imparted and sometimes can completely ruin the feel of an entire anime. I wish the companies would just invest more money and time into making a good dub