Are the scriptural descriptions about the glories of the holy name exaggerations?

From: Devdatt

It is explained in the scriptures that by Chanting Lord’s names one gets rid of so many sins that he will be unable to commit those many sins. and there are others which glorify the potency of the holy name. These sometimes appear to be like exaggerations. Because I heard one explaination that these results do not appear to us because we commit offences. Then if that is true the these glorifications should have asterik marks as there are exciting advertisements of the products but with asterik marks. If such is the power of the holy name then why some poeple leave Bhakti after chanting holy names or they fall into depression even when they chant the holy name regularty?(Please clear this doubt which my dirty mind is harassing me off)