We use BioSpot on our dog (lab) but I can see if the dog is very short coated that you might have problems. We've had no problems with it at all. After I put it on her coat, I'll take a comb and help distribute it better and quicker.
You might have one dog in a thousand that have a reaction - but that's not saying the product is bad. Even regular vaccines can cause reactions in certain pets. That doesn't mean ALL vaccines are unsafe.
Its a caution thing but take it into perspective !