I send a lot of messages per day -- somewhere between 10 and 200.
And I probably get a greater-than-average percentage of replies back due to what I'm messaging people about.
It's usually:
1.You're not sharing, so I'm killing my upload/s to you. (replies back are sometimes hostile, but generally quick)
2.You're sharing trojan-infested files (ie: regular Kazaa versions) -- the replies back to this range from silly, hostile, to scared shitless.
3.My upload or download to/from you is very slow (like 0.1 KB/sec or less) -- I can tell you how to cure that... (least likely to get replies back, but generally friendly ones if at all.)