Its not just meeting the guy. Your family and the other family meet as well. Your parents have more experience in determining the character of someone than you yourself might. Your parents meet his parents and through talking suss out the characteristics and qualities of the family. Then you ask around to find out what other people know about this family and whether they are suitable or not. Its also not just based on one meeting usually. The families meet three maybe four times.
Arranged marriage is usually quite good in determining compatibility. Of course whether its arranged or not the true character comes out when you actually live and share life with the person.