Is there a well-validated questionnaire that only measures a subset (visual, attention/distraction) of user satisfaction? Let's say I want to know where to put my ad on an iPhone screen, and I want to design an experiment to find this out. Since I am primarily interested in the visual aspects, and whether the ad is too distracting or not, I want to find some standardized questionnaires that only measure these aspects. Does anyone know any good instrument?
Among all the questionnaires and models which claim to measure user satisfaction, there is no such as you describe. However, "user satisfaction" is badly defined in IT studies and frequently conflated with a multitude of other concepts. It is possible that you will find a questionnaire designed to measure a concept with a different name, maybe the system acceptance of the TAM people, and that this concept is actually close enough to your understanding of satisfaction for you to be able to use it.
But I am not sure that you need such a visual questionnaire. As far as I understand you, you are not interested in creating a predictive model for visual satisfaction, or measuring the factors of an existing one. You are interested in delivering an app which satisfies your users, period.
For this, you can design what is commonly known as A/B test among practitioners (or better, use more than two conditions). Satisfaction will be the dependent variable; measure it with a generic satisfaction or usability questionnaire. As independent variables, you don't need to use any visual factors; just use a single variable: different versions of your app, with the ad placed in a different place in each. A beautiful side effect is that you end up with only two variables and can use a simple t-test for evaluating the results; there is no reason to set up a multivariate model, which requires advanced statistics.
For the questionnaire choice, some questionnaires will be better suited to your case than others. The ones coming from core IS will not be very good; they measure variables like how accurate the information is and how much support you offer. The HCI ones will be better. But I don't have them right now here to look through them and tell you, and besides, I don't have the pure usability ones.