When I was a youngster, I took a notion. To be respected, you must act respectful. I used this as an excuse to disrespect adults around me. After all they didn't deserve respect with their temper tantrums, selfishness, and so forth. Right? Wrong. Christian character aside, common courtesy demands the respectful treatment of elders. Plus, the commandment doesn't say honor your parents if they are honorable. It doesn't say love the lovable.
"Honour thy father and thy mother: that thy days may be long upon the land which the Lord thy God giveth thee," Exodus 20:12.
"As the Father hath loved me, so have I loved you: continue ye in my love," John 15:9. Heavenly Father certainly doesn't wait to love us until we are perfectly lovable. Jesus doesn't only give eternal life to the perfect. Their love is unconditional.
Somehow, I don't think this applies only to parents. In my mind, it applies to spouses and children. The family is sacred and matrimony is holy. Our most important relationships are special and set apart for a higher purpose. Still, nobody will attain perfection on earth. So how is it possible to courteously honor and respect someone who doesn't reciprocate or someone that doesn't 'deserve' it? At first do it for Jesus. "Verily I say unto you, Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me," Matthew 25:40. As time goes on and the capacity to love charitably increases, do it with a goal of rekindling or solidifying familial and marital bliss. Just do it.