So yesterday a buffoon sends out a mass email cc'ing rather than bcc'ing everyone in his mailing list. There were understandable complaints in some quarters, but quickly the tone changed as in-boxes filled with emails from various social media experts offering parodic investment opportunities in Nigeria, deals on pharmaceuticals and announcements that the email list had been sold to spammers.
Perhaps the context of a lazy Friday or the overlapping of the recipients' networks contributed to this interesting example of community forming around a shared sense of implicit (albeit most definitely not explicit or universal) permission. But, the sixty-odd contributions so far have crucially not expanded the distribution beyond the original list and there is a sense of trust that they are all sufficiently web-savvy to limit any damage that has already been done.
If you can engender that trust amongst your potential customers, it seems that people's human-ness shines through even when you screw up.