I agree that stating you have a deck of cards (weather normal or not) is bad patter. obviously they can see what you're holding. But i think having a spectator shuffle the cards before you even begin removes all question of trick deck or any sort of stack.
to me it seems why not be as fair as possible? no one is going to say "hmm he let me look at the deck too much"
However, someone might say "he didn't let me look at the deck in the beginning"
Who are you performing for that will, completely out of the blue, think the deck may be stacked and that you have memorized that stack?
Also - I know at least one guy that lets his spectators shuffle both one-way forcing decks and also Svengali decks.
I think magicians assume people care about magic and actually research it on their own. Most spectators don't care about magic. They like being entertained, but unless you challenge them to find your method, they're not going to put any effort into it.