Depends - how keen would you have been on sitting in your A Level Sociology lesson when the topic comes up, listening to all the other students parroting the attitudes of their parents about workshy criminal layabouts in dirty council houses, being thick, ugly, fat, violent and enjoying the visceral satisfaction of enunciating the word Underclass for 'these people' - and knowing that they are describing you and your entire life as their faces hardened and their lips curled to say the word?
Like many words and phrases, it became pejorative almost the moment it was coined, at least in part due to the obvious commonalty with Untermenschen.
As a concept, to find a way to describe the poorest, most marginalised and vulnerable without using historical/non English phrases such as peasantry, serfdom, peons, untouchables, pariahs, ghetto (as from Antisemistism and when transferred to Black Americans), etc, it's difficult, because whatever is used is always going to become an insult, just as every word and phrase for describing disability, particular illnesses and needs will become one shortly after it is adopted.
It all feels pretty crap when you know it's a word to describe you, though.