There is actually what appears to be a related bug I found when doing some testing. I don't know if it's the cause of what you see or not but to duplicate:
1. Use a clean browser free of cookies. Disable javascript (I use Noscript).
2. Find some trades in your toplist which have 0 ins and 0 clicks. (Preferably to your other sites so you are not technically cheating anyone!) Keep track of which site you clicked on first and second.
3. Visit your site as a type in.
4. Click on the trades identified in #2 with 0 clicks and 0 ins approximately 1 second apart. This probably won't work if you chose to filter toplist clicks in settings->out and redirect them to a special page. It didn't work for me.
5. Check your stats after a minute or so (if high traffic, if not it may take longer). You will probably notice the first or second site you clicked on now has some clicks - apparently for some reason TP is counting the clicks OUT which you just made to those trades. You'll also notice it still has 0 IN.
I'm not sure which other conditions will trigger this. It looks like it only messes up on toplist clicks with javascript off right now but it's possible the bug is manifesting in other undetected ways which I'm not seeing.
It's not a big deal as all software has bugs and this probably happens in rare conditions but you guys might want to check close this one to make TP even more perfect.
In a worst case scenario I believe if a bot came and started clicking on your toplist in sequential order it might very well award +1 "click" to the first or second trade - one for every toplist click on your other trades. So at the same time it's probably not a "brush off" bug either.