But Harrison's Deckard isn't meant to embody that "ethics/work inspector" as a good actor would.

He is meant to portray him as a detective who is not that good with pretending to be someone else would.

Harrison might or might not be a good actor, but Deckard certainly isn't supposed to be a good one.

> Deckard certainly isn't supposed to be a good one.

Why not? He's a seasoned detective with a track record, why's it so hard to believe he picked up some tricks?

He's supposed to be a detective doing investigating work and killing robots. Not a method actor.

J.J. Gittes is also a seasoned detective, doesn't mean he would be great acting.

No, he's not. He's sushi, cold fish. He doesn't even know for sure if he's human. He can't be a good actor.

Actually, if he's a replicant made to believe he's human, he might even believe he was doing a good job, because he'd be clueless about what good acting is supposed to look like.

No, he's a replicant who believes he's a seasoned detective. Nothing Deckard believes about himself is true.

Or, if you believe he's human, his the typical hard-boiled detective, he did behave in the way Ford portrays in the movie. Not subtle, not particularly clever.

It’s just about the only comic relief in the film. Possibly it’s acted that way deliberately.