If you have nothing to hide, most people would open the door and say, Yes, please come in and and lets dispel any information you have because its false.
This is one of the most BS statements the cops use all the time. Two cops came to my door a few years ago looking for some guy they said was dating my daughter(she wasn't dating him, BTW) and wanted to search my house when I told them he wasn't there, this was about 3 AM, couldn't come at a decent hour.
I asked to see a warrant and they gave me that crap line about "if you have nothing to hide". I asked them two questions,One: "Do you think the constitution was written to protect criminals or ordinary citizens? If you do then your question makes no sense, warrants are required to protect my rights as a citizen". Second question was this:" Will you allow me to go over to your houses right now, wake up your families and make a thorough search of your houses? If so then I will let you come in and search mine after I finish with yours". They couldn't answer the first question and got down right huffy over the second one and refused to let me search. I went right back at them and asked, "why? do you have something to hide?". They left right after that.
should read "If you do believe it protects citizens then your question makes no sense, warrants are required to protect my rights as a citizen".