Different cultures may have varying thresholds for what is considered tactless, so context matters. What's normal in one culture could be seen as a tactless remark in another.
Pro Tip 2/3
Negative Connotation
'Tactless' usually describes negative behavior and can suggest a lack of empathy or social skills. His tactless joke during the solemn ceremony was frowned upon.
Pro Tip 3/3
Social Relationships
Being tactless can damage relationships and hurt people's feelings; it's more than being just 'honest'. Calling her singing bad was not just honesty, it was tactless.