Sorry if this is has been posted before, but I just noticed it, and I was on my way to bed, so im making a quick post before I forget.

Here is my specs.
Windows Vista Ultimate (6.0.6000)
Windows Live Messenger 8.5.1018
Messenger Plus! Live 4.50.0.312
Skin: No-Ads 8.5-9.0

Now.. Maybe if other people can do what I do to see if this happens for them too...

Step 1 - Disable custom emoticons from messenger options menu. (Close/Open test chat)
Step 2 - (Maybe optional.. but it happend in my case) Have someone send you a custom emoticon.
Step 3 - (Maybe optional.. but it happend in my case) Try send that very custom emoticon back to them.
Step 4 - Send that line again, with /noicon in front of it then.
Now you should be able to send/recieve custom emoticons, but if you goto the messenger options, you can see they are disabled.

Odd I say... Might just be the way /noicon works or something.