“Also, if you check out the shidduch after an emotional relationship has been established it may be difficult or almost impossible to break even if there is something nefarious in his/her background. “
If there is something nefarious in HIS background, the shidduch is oys,and my daughters themselves would say so. If it is something in his FAMILY background, that is not so glatt. A fine boy should not be punished because he has an uncle who stole money, or his parents are amei haaretz.