Nowadays persons have a kind of use and throw attitude even for human beings,which makes it nearly impossible to trust anyone. Well inspite of being actually a big deal I have an unmistakable solution for this.
To conform that one is trustable or not,we have to undoubtedly check his company or the persons he loves to spend time with. By which you will come to know his personal opinion,since people generally search comfort within their company and that comfort they get between persons who share a bond of common beliefs,interest etc. Hence you can say that
OUR COMPANY REFLECT OURSELVES
You should look after whether person on check is kind,loyal and faithful towards other or not,if not then there is no guarantee that he will not do same with you as well. So I guess
YOUR NATURE CAN BE PREDICTED BY EITHER YOUR COMPANY OR YOUR GENERAL BEHAVIOUR TOWARDS OTHERS.
Persons usually face this problem during many times from family to friends as to determine the actual face of someone behind that fake mask,so i think its quite helpful for everyone out there in dilemma.