- Non-obvious business model - It's not obvious how you profit from the raffles, whereas charging money is generally easier/quicker to understand
- Use of memes (e.g. http://muxme.com/giveaways/56-25-toys-r-us-gift-card ) doesn't inspire confidence (may be a personal quirk of mine)
- Layout/design - My initial reaction when the page loaded was "Oh, it's a penny auction site", which are known for being borderline scams. Obviously it isn't, but that gut reaction is difficult for you to overcome (I'm thinking of sites like swoggi.co.uk when I say penny auctions)