If you're using jsp or jsf technologies, you don't need to know beforehand what getters and setters a object has before you access it as a bean. However, understandably, you may want to offer alternative views for these items.
So generally speaking, my approach would be to establish an enumerator type which all Product classes must return in an abstract method. The method would be derived from all its children and give you an indicator of what type you're dealing with and you can manage it accordingly. In otherwords, if your current object has type "Trousers", then you include a view for that object called views/Trousers.xhtml. Alternatively, rather than return an enumerator, you could return the actual view for that object (be careful since two product types may share the same view i.e. Jeans + Trousers, so don't use that as an indicator of type).
In the view, you know the object has already met a precondition that it is of a certain type or has explicitly indicated that particular view. At that point, you can safely call upon the properties of that object that you know it'll have.
I hope that answers your question.
Edit:
That may not scale well depending on the number of products and how often you have to change these products. In that case, I recommend you return a string indicator instead. With that string, you can establish some patterns such as using a view with the same string indicator, etc. You could conceivably use the class name as an indicator of type, if otherwise not overridden in your derived classes.
