Recently I have been doing some reading and I came across an article that say that saliva was extremely  hostile to sperm because of its acidity.   So this can have the same effect or worst than that of Lubricant!  And all along I was thinking that it was okay.
 
Sometime to make things a bit more wet down there my dh may spit on the opening of the vagina for extra lubricant.  We never knew that it could be doing harm to our baby making process! 
I just decided to share this piece of info. In case any of you were using the method instead of lube, thinking it may be a safe cheap way.