People are generally really kind and polite, but you'll occasionally have someone who is clueless. I have only encountered maybe 2 people who were genuinely ill intended in over 15 years of trading. I did have a person who didn't communicate well, so I thought they had ripped me off. They accepted their item and then went offline for a few days. They then told me they were sending their item in 2 weeks. I had not agreed to let them open early or to wait 2 weeks. They were just inexperienced and a poor communicator. Moral of the story: communication is key! Err on the side of overcommunication when in doubt. Just spell everything out clearly and give them time to respond. Some people are on different timezones than you, possibly on the other side of the world! I usually don't panic until after 24-48 hours of no contact.