I know this is a stupid question but there are many arguments. I only want the best practice argument here.

UI BLL DAL

how should data from the UI be passed all the way to the DAL? Remember - we are using clear seperation here for things like easy swap in/out of the layer in question with less impact time but still a solid solution..

For example, the UI could be a search page where it has x amount of input fields. Would all these fields be bound to some model/entity then passed to the BLL for validation. After validation succeeds, then should that entity be passed to the DAL? OR should the DAL have the data inputs in its rawist form? (i.e parameterised data like string, string, int etc... rather than an entity object) What about the BLL data being passed from the UI?

Of course, I believe in OO (duh) but sometimes it is tricky to figure out the "right" and best practice (Without it being overly and unnecessarily over the top OO) of the architecture of such a solution.

What is the best approach here?

put simply: data being passed FROM the UI all the way to the DAL, should it be without it being wrapped in a DTO entity type object or should it be wrapped in a common object? Why or why not?