According to you, trust and reputation, are they related?
They are slightly related imo.
Trust represents the honesty or otherwise of the user; if I trust someone, I can recommend them as escrows or go first in a deal.
Reputation is more about a user's personality and what they are known for, it could be likened to popularity or attitude. A user can have a bad reputation, maybe cause they do not see eye to eye with others on certain topics, but they could still very well be trustworthy.
What do you think about being trusted by a guy you don't even know? Honestly, even when I deal with someone, I don't think I can trust someone (like me) to send $ 600 in advance. Was I too skeptical when making transactions? It seems I have lack of trust?
No, you are not to skeptical. The internet is filled with scammers and one is right to be very skeptical with any interaction involving money. The user may have been lucky not to get ripped off in this case, but making financial decisions based on sentiments is never a good idea.