His Wikipedia entry mentions that Bergey studied at the Pennsylvania Academy of Fine Arts for four or five years, but this more detailed source mentions that his attendance was at evening school and that there is no record of his having graduated. Nevertheless, he probably received at least a little good training. Bergey worked at the Philadelphia Public Ledger newspaper for a while, but then drifted into painting pinups and pulp cover art. By 1948 he also was busy doing cover art for paperback books.
Here are examples of his work.
This cover is pretty standard science-fiction pulp cover fare from those good old days featuring a monster, a heroic man and a scantily-clad woman in distress. One difference is that the illustration is slightly better done than what was usually seen on sci-fi mags ten years earlier.
Here we have pretty much the same thing, but with a better view of the BEM (bug-eyed-monster).
Two more Bergey sci-fi pulp covers. Note the similarity of the space ships diving towards the lower left corner of each cover. As for those large images of women, note that they are well done. It seems that Bergey liked to paint beautiful women and was good at it.
The lion in the background is also convincingly done.
Bergey offers this face that's part glamour and part girl-next-door -- a well-dressed version of Bettie Page.
The postwar paperback edition of Anita Loos' best-known book.
Bergey was a Philadelphia guy, so he also did a cover for the town's most famous magazine.