Neither do I. if you reread my post you'll find we're on the same page. "I'll take it" is fine if you actually intend to buy it. It's the people who post that and then disappear like Jimmy Hoffa who annoy me.+1
I post "I'll take it" after I pm a seller to buy at his asking price. I do it mostly to alert the seller if they have notifications sent to their phone.
I post "pm sent" if I send a question or offer. I post in the thread for the same reason as above.
I see nothing disrespectful in that.
"PM sent" doesn't bother me at all.
Live and learn.
At best I'd think it was wishful thinking. You guys who get hostile at lowballs might want to reflect on how much money is at stake. I have given items away that I have had lowball offers on before. I'd rather it go to charity than be taken by someone who would probably re-sell it as if it were gold plated after telling me how crummy it was.