He is polite to a fault.
Is the kanji for ばか 「馬鹿」？
Is this usage a set expression – that is, using ばか as one would use 大変 to emphasize a description?「ほにゃら」ばか「形容詞」だ
@ericaw
Yes, it is 馬鹿 (stupid). バカ + adjective/adverb = too much (or unnecessarily) + adjective/adverb. バカ丁寧だ is a shorten form of バカバカしいほど丁寧だ or バカが(頭に)つくほど丁寧だ
You can also say:
彼女は馬鹿正直だ。(also spelled as バカ正直 or ばか正直) = She is such a naive girl. / She easily believes everything.
この商品はバカ高いな！= This product is way overpriced!