Use of the word is out of ignorance - not for intentional disparagement - would be my guess. It's the Archie Bunker syndrome.
Main Entry: in·fa·mous
Etymology: Middle English, from Latin infamis, from in- + fama fame
1 : having a reputation of the worst kind
2 : causing or bringing infamy : DISGRACEFUL
3 : convicted of an offense bringing infamy
- Kirt Blattenberger