vendor skimming?

I decided to check out a vendor's email sequence and I noticed that they swapped affiliate IDs within the sequence (it's late in the sequence in fairness). It made me think about the couple of unusual days I saw promoting them with dozens of form impressions and no conversions, it would happen after a few good days with upsells, then the next conversions would come in without upsells.

Wondering what people's experiences are with this?