The actor who plays Samut is Chinese, that's why is dub
As far as i know, in Crazy Handsome Rich, the DUB was done on purpose. It’s a comedy, and the bad dubbing is part of the comic style. For other series, it’s usually the same reason as in Battle of the Writers- some of the actors aren’t Thai, so they had to be dubbed. Another example is the actor who played Rek in My Engineer- he’s Chinese too, so they dubbed his voice. And sometimes, when only a few scenes are dubbed, that’s usually because there were sound issues while filming, so they had to DUB to make sure we can hear everything cleary. This is pretty common when there are any thenical sound problems
For other series, it’s usually the same reason as in Battle of the Writers- some of the actors aren’t Thai, so they had to be dubbed. Another example is the actor who played Rek in My Engineer- he’s Chinese too, so they dubbed his voice.
And sometimes, when only a few scenes are dubbed, that’s usually because there were sound issues while filming, so they had to DUB to make sure we can hear everything cleary. This is pretty common when there are any thenical sound problems