Stop. Telling. Me. What. To. Do.
That should be my mantra right now.
Realization#8: No matter how well-intentioned the advice, nobody knows your baby like you do.
It's really hard to be tactful when my mom says "she doesn't like when the infant seat vibrates." How the hell would you know? I put her in that shit, flip the switch and she passes out. She's only crying now because you pressured me to put her in the seat instead of holding her AND SHE WANTS TO BE HELD. Which is another fun one: "you can't hold her all the time, just put her down." You know what? No. I want to hold her, I like holding her and she likes to be held. It's important for us to bond physically. So shut up and let me parent my child. Kthnxbai.
In conclusion, I don't recommend being rude to people who say stupid shit about what your baby likes and dislikes after spending five minutes with them. However, it's kosher like Hebrew National to be honest with these folks and say "Actually, she loves that! She just wants to be held right now, but she'll calm down in a minute." (And then rant on your blog about how obnoxious people are...)