Who spoils the ninken?
I think Kakashi and Iruka both spoil the ninken, but Kakashi doesn’t consider it spoiling them… because he’s been manipulated by them over time.
He’s known the ninken most of his life, and trusts them completely, so when they say they need something, he’ll just get it for them, no questions asked. They need fresh, human-quality steak so they can ‘train harder and be better on missions’? You got it. They need a massage once a month because ‘the stiffness in their muscles will hinder their ability to work, and the strain could cause injury’? Kakashi will absolutely send them off on a spa day.
Iruka always tells him that they’re just manipulating him, but he feigns ignorance and doesn’t do anything about it, because the ninken usually don’t ask for much, and he thinks they deserve all the things they want 
As for Iruka, he spoils them because he always falls for those puppy dog eyes. Even when they’re not giving him the look, they still melt his heart; and he just can’t help but go out of his way to give them extra treats when Kakashi isn’t looking, surprise them with new toys, and just generally shower them in love.
He knows that they’re fully trained shinobi hounds, but when they’re off-duty, he can see that they enjoy being normal dogs, and he loves watching them have fun and getting excited over normal dog things. Especially Pakkun, who likes to pretend so hard that he isn’t enjoying himself, even when his tail is wagging so fast it could almost be a propeller 
What do you think?