1. in a way that shows poor judgment about what is appropriate or attractive
2. in a way that lacks flavor or taste

Examples

• The room was tastelessly decorated with clashing colors and cheap furniture.
• He tastelessly made jokes about the tragedy during the memorial service.
• The expensive dress was tastelessly covered in gaudy sequins and rhinestones.
• She tastelessly bragged about her wealth in front of her struggling friends.
• The food was tastelessly prepared, lacking any seasoning or spice.
• The movie was tastelessly violent without serving any artistic purpose.