The problem is Jehovah's Witnesses actually take the scriptures seriously. So they follow such scriptural teachings as:
Matthew 28:18 "And Jesus approached and spoke to them, saying: "All authority has been given me in heaven and on the earth. 19 Go therefore and make disciples of people of all the nations, baptizing them in the name of the Father and of the Son and of the holy spirit, 20 teaching them to observe all the things I have commanded YOU. And, look! I am with YOU all the days until the conclusion of the system of things."
Luke 10:1,2 "After these things the Lord designated seventy others and sent them forth by twos in advance of him into every city and place to which he himself was going to come. 2 Then he began to say to them: "The harvest, indeed, is great, but the workers are few. Therefore beg the Master of the harvest to send out workers into his harvest."
Acts 20:20 "while I did not hold back from telling YOU any of the things that were profitable nor from teaching YOU publicly and from house to house."
Acts 5:42 "And every day in the temple and from house to house they continued without letup teaching and declaring the good news about the Christ, Jesus."
Witnesses are not coming to your door to "convert" you. They are coming to teach you what they understand from the Bible. What you do with the information is up to you. Their responsibility is simply to try to impart the info. They do not fall under the term soliciting, since all they offer, their time, literature etc. is free. They do have a "do not call" list. You don't have to make up any stories and lies. Simply say: "Could you put me on your do not call list please."
Prov. 6:16-19 "There are six things that Jehovah does hate; yes, seven are things detestable to his soul: 17 lofty eyes, a false tongue, and hands that are shedding innocent blood, 18 a heart fabricating hurtful schemes, feet that are in a hurry to run to badness, 19 a false witness that launches forth lies, and anyone sending forth contentions among brothers."
Prov.13:5 "A false word is what the righteous hates, but the wicked ones act shamefully and cause disgrace for themselves"
Psalm 119:163 "Falsehood I have hated, and I do keep detesting it. Your law I have loved."