Anything can be learned if you know the technique of how to do it. The same with people. How do you know who you can trust? The first thing is the persons body odor. Not the odor of the perfume, but skins own smell. The stronger the bad smell, the less you can trust the person. The one thing for sure, is the person with a bad odor is afraid. And one can not trust someone who is at fear or is anxious. Of course one can always help the person - if one is trained how to do it. The other point is the persons environment. Their mental condition (calmness, ability to differentiate and understand, ....) depends on how they keep their environment. A dirty, smelly, disorderly home/hosue/office/toilet/kitchen shows you the person has problems so will not be able to really listen to you and take your needs and wants into account. If you are interested in more tips let me know.