[_yb2s]

I realize this is a bit of a "no true Scotsman" but what you are talking about is a gross misuse of Bayesianism- where your own biases are incorrectly treated as extremely strong evidence.

I am partial to using unform priors over all possibilities, and then just adding in the actual evidence for which you can actually quantify its quality/strength. Your "prior" for a new situation is constructed by applying the data you already had previously to a uniform prior- not by fabricating it from whole cloth via your biases. In practice this may be impossible for humans to do in their heads, but computers certainly can!