The common practice in my home is before i make a Bracha i usually look around to confirm that there are no dirty diapers in the room or clothes that were dirty due to dirty diapers. After Havdalah Motzei Shabbos to my dismay, i found clothes which were dirty with Graf shel R’ei in the room which i forgot to check.
1)Am I Mechuyov to check the room for dirty clothes or my children for dirty diapers before I make a Bracha?
2) In the event the Bracha was made in the presence of these things accidentally, does the Bracha have to be repeated or are you not Yotzei in any way the Mitzvah you are performing at the time?
In our day and age, soiled diapers and clothes, on or off the child, generally provide a cover for the excrement. In such scenario as long as there is no smell emanating, one is not obligated to check. Although if there is some reason to believe there may be filth, it is proper to check. In such a scenario, even if excrement is found in a diaper or garment, any Havdala, bracha, tefilla does not have to be repeated.
See Pri Megadim Aishel Avraham, 79:9, Ishei Yisrael 52:18.