Well , why don't we try just investing small amounts in him.
Maybe we can catch him red-handed and force him to quit , before we go bankrupt

Trusting people without history, and without reputation with anything you want to call an "investment" is about as far from actual investment as you can come.
jambola2 realises that he is talking to BingoBoingo. He goes into coinchat talking mode.I am willing to invest 0.03 BTC.
I will send it to you , and will expect 0.0375 within 48 hours.
Either - 7.5 mbtc profit , or one less scammer on the forums ( win - win )
Tell me your bitcoin address now.
This is a rather poor proposal. Why do you want to enable this scammer so badly.
If they pay you back and then scam later, you will kind of both look like scammers. This is a poor value proposition for you. See below.
So as it stands, I vouch for this service up to now...but any discrepancies and/or losses in the future can not be attributed to my vouch.
Of course all the future losses will be your fault too! Send all your BTC to the scammer, bankrupt the first casino and then vouch. Without doing this you are scammer too.
Please read about why you shouldn't feed the scammers:
https://bitcointalk.org/index.php?topic=106391.0
The rest of this thread may also be informative:
https://bitcointalk.org/index.php?topic=236971.msg2510149#msg2510149