I'm sorry, but your question wasn't clear to me. Your discussion about formats ("00:00:00" vs "@ 12 PM") gave me an impression that you want a different format; now it seems it's irrelevant (or marginal, at least); you're sying that you're actually getting an unexpected value.
Please try converting your date with "o" format:
Console.WriteLine("{0:o}", item.shippingDateRequested);It includes not only hours, but also timezone offset, which might give you some extra information. (Honestly I have no idea whether AX returns timezone in DateTime structures.)
If you can, do some debugging to find out when the value changes. (You can debug CIL code in AX using Visual Studio.)