So Michael Keaton was in the last two "Best" films. I wonder if he can make it a trifecta. He's on a roll.
Well, yes that's great if he finally wins for Best Actor too!
I know Eddie Redmayne was good in
The Theory of Everything, but I would have preferred seeing Michael Keaton win for
Birdman last year. I also liked Benedict Cumberbatch in
The Imitation Game better than Redmayne. Coincidentally Benedict also played Stephen Hawking in a British television movie, mainly portraying Hawking's early life. Redmayne and Benedict were on one of the
Hollywood Reporter group actor interview shows (posted on Youtube) last year and surprisingly it was never brought up that they both had portrayed Stephen Hawking.
If I white host commented on two black people looking alike, I wonder what the reaction would be. Didn't care for Rock's joke about thinking Sam Smith was George Michael.
I wouldn't put it past Ricky Gervais, and he likely wouldn't rule it out either with his brand of humor.

Anyway, to answer your question, it probably depends on the context. If it was a funny joke and the context matched the joke, then I'm sure most people would laugh. You can't help laughing if your funny bone is hit, even when the joke might be scandalous/ considered in poor taste. There's always that fine line with comedy/ sarcasm.
Speaking of which, you should know PeterG, especially since you are one of the coolest tongue-in-cheek posters on FSU.
Besides, Sam Smith does look somewhat like a young George Michael.

People do look like each other sometimes, ya know.
If Joseph Fiennes can portray Michael Jackson in an upcoming road film (with Stockard Channing as Elizabeth Taylor, and Brian Cox as Marlon Brando), I mean anything's possible.

I can't wait to see this. Clearly the hair and makeup will have to do a big part of the job to assist the fine Joseph Fiennes. And, he's absolutely got to work on getting the whispery voice right and those smooth moves/ innate physicality down/ up to MJ believability.