If your friends profile says they commented on so and so’s status or pics, you can click on it and see it.
unfortunately, I haven’t been able to view any of the profiles that i have stalked on facebook either. Facebook’s default is to set profile to private automatically for the users privacy, unlike myspace where we have to go in and set it to private ourselves.
Facebook is probably the most secure social networking site out there, so I don’t think there’s any way you’ll be getting into someone’s private profile other than just adding them as a friend.
Of course you can always make another profile and add them on that one, I guess.
Anyways, good luck! 🙂