Let the page types implement a marker interface interface, ie IDontIndexMePlease, then this _should_ work:
PageIndexer.Instance.Conventions .ForInstancesOf<PageData>() .ShouldIndex(x => !(x is IDontIndexMePlease));
Of course an attribute could be used as well but then the ShouldIndex expression would be a bit more messy.
Is there a way to write this code simpler?
I would also like to propose to by default exclude container page types from the index.