1/ Cylons usually hit what they aim at, Stormtroopers never do.
2/ Cylons would never be defeated by Ewoks.
3/ And look at 'The Empire Strikes Back': They are fairly effective at destroying the Rebel base on Hoth, but let every important Rebel -- Leia, Han, Luke -- escape, as well as all the transports. At Cloud City, Lando has no trouble capturing them and keeping them locked up. Then they the let Lando, R2 D2, Leia, and Chewie (with C3PO strapped to his back) to escape without a scratch. And they don't even bother to take cover from Chewbacca.
4/ But the #1 thing that shows how stupid they are is in 'A New Hope' in the desert on Tattoine when the stormtrooper says, "Look sir, droids." Wouldn't that obvious by R2D2's tripodial tracks?
Apparently, Cylons had to walk that way because of the restricted movement of the actors inside the cotsume.
In the new modern version of 'BattleStar Galactica' Cylons can also be one of 13 android types that completely mimic humans. Unfortunately, these new Cylons just aren't dumb at all.