>I found an interesting problem. Here is the element
>
>

><div class="col-md-6 col-lg-6">
>                        <input type="text" name="opCode" id="opCode" ng-model="currentOperator.opCode" placeholder="Operator code" class="form-control ng-untouched ng-valid ng-valid-maxlength ng-hide ng-valid-required ng-dirty" ng-maxlength="6" ng-show="isNew" ng-required="isNew">
>                        <div class="field-validation-error ng-hide" ng-show="form.editOperatorGeneralForm.opCode.$error.required && form.editOperatorGeneralForm.opCode.$dirty">
>                            <span>Operator code is required.</span>
>                        </div>
>                        <div class="field-validation-error ng-hide" ng-show="form.editOperatorGeneralForm.opCode.$error.maxlength  && form.editOperatorGeneralForm.opCode.$dirty">
>                            <span>Operator code cannot exceed 6 characters.</span>
>                        </div>
>                    </div>

>
>Please note the ng-dirty class applied although there is also ng-untouched class.
>
>If I remove the placeholder, this element and another element also with the placeholder no longer have ng-dirty class applied.
>
>That's weird.

This seems to be a known problem https://connect.microsoft.com/IE/feedback/details/856700