They are fast. My BF and I just moved into a house. It is pretty much brand new but since we are getting my yorkie girl soon, I went in the day before we moved and vaccumed the whole house. My BF said "what are you doing, the cleaners just went through the house." I told him, you never know! What if they forgot to pick something up, I'm sure the puppy will find it, and I'm not taking a chance.
You can never be too careful.
