A "pettifogger" is a term used to describe what type of petty, underhanded or disreputable professional?

In its earliest English uses, "pettifogger" was two separate words: "pettie fogger." "Pettie" was a variant spelling of "petty," a reasonable inclusion in a word for someone who is disreputable and small-minded. But why "fogger"? It may come from "Fugger," the name of a successful family of 15th- and 16th-century German merchants and financiers. Germanic variations of "fugger" were used for the wealthy and avaricious, as well as for hucksters. In English, a "pettie fogger" was originally a small-time operator of a shady business. We're not sure why the word came to be applied specifically to lawyers, but it appears to have initially referred to lower-status attorneys who argued the smaller, less important cases.

The lawyers called pettifoggers spent their time arguing about matters of small importance. The term became popular, and spawned derivatives like pettifogging. These survived the original term, which is now considered archaic, but we retain in the latter word the idea of somebody who places too much emphasis on trifles or who quibbles about minor matters.