In standard English bastard is of course a noun: "You rotten bastard". I don't recall hearing it used as an adverbial or adjective in other Englishes, but it is in my own English, the Jarrow version of the Geordie dialect of North East England.
I remember my father saying, probably in the late 60s on hearing of alleged drug offenses, (maybe it was at the time of the infamous Mars bar bust): "The Rolling Stones? I wish they'd roll right over the edge of a bastard cliff." Here he was using bastard as an adjectival intensifier, giving the cliff concept a little more colour.
Another time I remember him being asked about the whereabouts of some ne'er do well acquaintance, and his reply: "Behind bars. Where he bastard well belongs." Adverbial bastard always conjoined with well. And like its adjectival kin its purpose was to intensify. "I bastard well won't go!" would normally want stress on the won't. The best equivalent to that clause in standard English would be, "I won't go under any circumstances".