A smart, skillful play = Placing wards to avoid ganks, then counterganking the enemy jungler with help from YOUR jungler when he arrives to gank you. Predicting a flash to land a vital skillshot and win a duel or get a kill.
A smart play that is frustrating for the enemy = Warding the enemy jungler's blue buff, then 4-man ganking him there. Five man diving bot tower and then taking Dragon.
A just plain frustrating that isn't really smart OR skillful = Standing inside your wind wall as Yasuo to be immune to auto attack and spells for a few seconds. Pulling an ally out of harm's way with a Kalista ult or a Tahm Kench devour.
A DUMB and frustrating play = Avoiding a skillshot as Yasuo by mashing Wind Wall accidentally at the right time... even though the skillshot came from a bush BEHIND you. Lee Sin kicking a Garen about to kill you away from yourself and accidentally killing an enemy you didn't know was there because the ult damage scales of his absurdly high health.
The difference is one of degrees. Smart plays involve clever thinking. skillful plays involve good use of mechanics. They can both STILL be very frustrating if it feels like the enemy didn't have a fair chance to even TRY to save themselves or outplay you. Then there are a ton of absurdly easy mechanics that infuriate people they're used against but can't really be called "smart" or not because they're simple button presses and kinda idiot proof. NOT using a kali ult to pull a support away from a gank would be dumb... but doing it doesn't make her pro. It's just a thing she does. Pretty frustrating for the enemy tho, since there's no real way to stop it. Then there are glitches and plain old DUMB plays that work because they mechanics involved are broken, poorly designed or just plain overpowered. These are almost ALWAYS frustrating.