I don't see the point in introducing kids to 'bad' foods at such a young age. I guess if they've never had it they don't know what they're missing out on. Like what is the point of giving a one year old a bottle with fizzy drink in it... Give them water all the time and they don't know what fizzy is.
My DD is 3 and refuses fizzy drink whenever she is offered it. She'll see me drinking coke or something and tell me that she'll drink coke when she is a grown up but she doesn't like it now.
I do remember the novelty of giving DD tastes of things when she was younger, but definitely not under 6 months, and definitely not something like sour cream!