Where's the "fraud"? How can the ETF be "manipulated"? Over the short term, excessive speculation by ignorant or corrupt traders can provide crazy price swings, but over time there will be a direct correlation as the above chart shows.
Most experts think that commodities are a good hedge against inflation. Why bail out now when inflation is low and this product is relatively cheap? IMHO, this a long-term hold and flitting in and out will kill your returns.
And by the way, there are hundreds of ETFs, from broad market indices to specialty sectors. They are a cheap way for the average investor to get broad exposure to these areas. These are certainly NOT "a trap for the small unsuspecting investors."
Most unbiased advisors argue that ETFs offer the BEST choices for small investors. Again, these must be LONG TERM holds. Chasing the flavor of the month (or year) will ruin your investment success for sure.