It's an annoying message to receive, but fun to give! More seriously, it is not a reason to trust someone, and a simple "I agree." or "Certainly. Affirmation of goal (set to bounce et al.)" is better, but I can't think of an actually committal response I've received recently. I can't think of many I've given. Admittedly, I usually propose a method. I'm not sure there even is a committal response, except for certain builds and certain move orders.
What really pisses me off is when I write three paragraphs of analysis to an ally, or enemy of an enemy, or a neighbor I don't know much about, and barely even get a response. Something like "yeah i dont like it either", preferably with random grammatical mistakes thrown in will not get me to trust you. This goes both ways. I respond to communication with trust, and am willing to team up with a guy who just stabbed me if he writes me a message. I've also been able to multi-stab with this a few times.