"I think it makes me more careful when examining fruits..."
That is a very wise conclusion to come to. What is often took as fruit in professing Christians can be seen in most who don't even profess to be Christians also.
I'm sure many here know someone (or were one) who seemed to be a saved Christian, well respected at church, good testimony before men, yet got convicted of sin and had their Christless state revealed... then really came to genuine repentance and told everyone at church of their new salvation... and almost no one believed them. "You've been saved. What are you talking about?" It has happened many times.
It should be said that love is the primary fruit of the Spirit... and nobody can really love who doesn't love God.
Jesus' words in Matthew 22:36-40 show that loving God is the prerequisite to loving your neighbor (and obeying any commandment). Of course, the opposite is true (none can love God and not love their neighbor as well). Love keeps God's commandments, otherwise it is not love.
"For this is the love of God, that we keep his commandments: and his commandments are not grievous." (1 John 5:3) See also 2 John vs. 6
Unbelievers are capable of kindness, the Bible affirms this. Luke says of the barbarians on the island Paul and his group were shipwrecked on:
"And the barbarous people shewed us no little kindness: for they kindled a fire, and received us every one, because of the present rain, and because of the cold." (Acts 28:2)
Just like some Christians are less like their Father than others, so some non-Christians are less like their father (the devil) than others. We've all been helped out by non-Christians at some time. Many are just not as hardened as others and do what they know is right and their duty. Others really do have selfish motives that they might not even be conscious of (possibly because God's Word has never searched their hearts). Not for us to judge why... just to know that kindness and self-sacrifice are not necessarily fruits of the Spirit. That goes for us too. We are not necessarily filled with the Holy Spirit b/c we help someone out, are nice, etc
True fruit comes only when all controversy with God is ended and Jesus Christ is exalted and on the throne of our lives. Acts 5:32 shows that obeying Jesus is the basis for being given the Spirit. That is the coming to the light spoken of in John 3:18-21. We cannot be righteous in God's eyes until we come to the light. It's important we uphold the biblical standard of fruit. Since that is often not done, we have the deception that abounds now.