One who thinks that a certain young man may be a suitable match for a certain young woman is not responsible to investigate the two and their families before proposing the mach. That is the responsibility of the parties involved and their parents. However, the prohibition against misleading one’s fellow requires that one not suggest a shidduch (matchmaking) unless:#1- He believes the two could be a good match and he is unaware of any reason the relationship should cause pain to either one.
#2-In his opinion, there is reason to believe that their meeting will ultimately result in an engagement. (it is wrong to waste a person time, energy and emotions!)
#3-He is not aware of any medical, emotional, or character deficiency that would render one party unfit for marriage.

Chofetz Chaim pg 218 day 84.