Why do democrats get upset when someone points out their ideas as communist?

[Owen]

A combination of two reasons.
1. When the word 'communist' is used in American politics, it usually references the USSR, early PRC, North Korea etc -totalitarian regimes. Therefore, calling the democrats 'communists' suggests they are totalitarian- which they are not. No one likes being compared to Stalin or Mao.
2. The democrats aren't communist. Although 'liberal' means something different in Europe (would mean the Republicans), the democrats are less 'american liberal' than most right wing parties in the UK and Europe- the conservatives in the UK and the democrats are very similar parties. Therefore, as democrats are at most centrist in the world political scale, calling them communists is just inaccurate.