in truth this isn't actually something I have done !!! However, I have performed and troubleshooted PCR much over the years including blood and components of blood like haem can definitely inhibit PCR if they are now removed from genomic DNA during purification; This might be present in stool and bile salts I know are present in stool and these also inhibit PCR
Ahmed, in stool there are several inhibitors, e.g. complex polysaccharides, Bile salts and heam derivatives and Urate. Attached two Reviews on the Topic.