she could affect my allergies
Our breeder had us visit and sit with her dogs to see how they affected my allergies. It seems like the best way to ensure that your sensitivities are not affected by the Basenjis you're looking at. I know this is not scientific, but it worked for us, and seems like a good practical step.
Also, our breeder, being responsible, wanted to ensure that she was placing her dog with a family where the allergy problem would not disrupt the transition to the new home.