Yeah, I agree with the OP; sometimes it can be annoying. For the most part I have had good fortune with my list threads, except for the Imdaar list thread where I specifically stated I wanted to run a MODIFIED Baron's focus list (with Krassis and an RG instead of the BH + Fel) and was told: "drop Krassis to a BH and upgrade the RG to Fel." O_o
Yeah sometimes advice comes from left field and totally guts the original idea, but it's nothing to be annoyed by. Just disregard advice that doesn't suit your style. No harm, no foul.
Honestly I think having someone completely disregard what you asked to be at least a little annoying. It shows at the least a lack of respect. Now if intent wasn't stated all's fair, but it seems a lot of people just look at lists without reading the words before or after and then start handing out advice.