Coming from both a buyer and a seller POV, I think having an auction start at the reserve price is fine because buyers know how much it is expected to be, at least. I hate auctions with a reserve and generally, I never bid on those because I wonder if it's a waste of my time because the reserve might be really high and not worth buying on eBay then.
As for why some things sell, some things don't. There's not really an explanation for that. I've even watched several auctions with the same item (once with the same photos and template because apparently the two sellers were "friends") and even that sold with a $50 disparity. Sometimes, it's all about timing. Maybe one listing is ending sooner than the other. Or it's just timing. Like the first listing will generate more interest, thus more bidders driving up the price. Then subsequent listings will be lower because there's a lower demand.
Oh, and sometimes it could be that the buyers are used to buying from that person. When I sold a ton of Juicy stuff last winter, I had a lady who drove up the prices on my listings and she bought a ton of stuff from me. I didn't know her personally, but she liked my customer service, s/h charges (esp. because I offered to combine for multiple purchases), etc. Plus, she knew I was legit. She was paying probably a good 10-20% more for my stuff than how similar auctions were going.
More about timing. In this economy, it could be as simple as that. Typically, aim for close to pay day time as being the end of the auction. I know personally, I tend to peek at eBay listings for goodies around the time I know I'll get paid (15th and 30th of the month). In addition, you don't want auctions on a Friday night or Saturday because people are not sitting at home checking out eBay.