[sonicggg]

Dealers lace it because it can't be easily detected. If they have access to this, then they may lace it with carfentanyl instead, if then you offer carfentanyl test strips, they'll find the next toxic thing to do it. It's just a cat chasing the tail.

[notRobot]

Most "lacing" of drugs with fentanyl is accidental contamination - for example when dealers use the same scales to measure different drugs and don't clean them between uses.

Dealers don't commonly go around lacing drugs on purpose - killing your customers is bad for business.