Welcome to the forum, Puff! I saw the word 'LOTS' and almost blew a gasket. They sell scrap pin 'lots' on Ebay and Craigslist, which are not genuine pins. We refer to them as 'Scrappers' as they are meant for the scrap pile. Always always always be vigilant of what you trade. I used to have over 1,000 pins, but after learning what scrappers were, I now have less than 700.
There are MANY great folks here to help you learn, and also important notes on pins on the PinPics website which can help you spot scrappers. I'm new to the forum as well, but very outspoken on this subject. Pin trading CAN be a great hobby, especially when you get that one last pin for a great set you've been working on for a long time.