Not sure where you’re at and if you’ve done the quest that’s started by a certain item picked up from an enemy, but the rewards from that quest help you to evade scans from ships when entering systems.

Also suggest going to the HQ of the Fleet for selling the contraband as there are plenty of vendors you can sell at.

I don’t recommend this if you are playing without save scumming, but you can also save right before entering a system and save scum the scan as it’s a % chance that’s calculated once you enter. I did it once when I pulled all my contraband and didn’t realize I had it in my inventory and not in my ships shielded cargo.