Your roosters do have tophats, you just don't notice as well because their single combs are so big, and because the Polish parents weren't very good quality (no offense meant, I just mean they didn't have a good enough crest or vaulted skull, so the traits don't pass onto the offspring, and thus - the offspring have hardly much of a crest)
Here's a Polish x Marans, his crest is a little more noticeable because his comb is smaller but still even he had a Polish parent with a smaller crest.
I've got loads of roosters and quite a few interesting mutts, but the threads for mutts come and go a lot. As for roosters - That is more of a "show em off" subject, so people usually post theirs either in the breed appropriate section or the pictures section.