I referred to this before asking this question.
AngularJs doesn't bind ng-checked with ng-model
If ng-checked is evaluated to true
ng-checked
true
What you could do is use ng-repeat passing in the value of whatever you're iterating on to the ng-checked and from there utilising ng-class to apply your styles depending on the result.
ng-repeat
ng-class
I did something similar recently and it worked for me.