What is your opinion on men who are into feminine boys?

Believe it or not, there are a lot of guys who are attracted to femboys. Some of them say that they are str8, and just sexually aroused by feminine side of femboys etc… Could they really be str8, or all of them are bisexuals? And also, what do you think about men who fetishize trans females (trans chasers)? Are they str8, bi or pansexual? For me, these questions forced me to think about sexual orientation types- Is it really necessary to classify? (Nothing against anyone)