Is your landing page your conversion page? If so, then 16% conversion is not that bad (depending on what you are trying to do). If your landing page is a pre-sell page that connects to a second page that is where the conversion occurs you are probably in trouble.
It really depends on your offer, but if you take 15% of your traffic and then get a 10% conversion rate on that traffic you pass, your true conversion rate is 1.5% of visitors performing an action for which you get paid.
Divide your average CPC by .015 and that is your cost per sale, if you are being paid more then you are profitable, if not you are losing money.
As for what to shoot for, it depends on the vertical and your payout. Shoot for 50% transfer rates and you will probably make money on most products.
If you have cheap enough traffic you can overcome bad landing pages, if you have a high enough payout the same is true. Regardless, improving the landing page by testing is only likely to improve your bottom line.
One other note that new people often overlook when studying their stats - it is not about the transfer rate from your page it is about the overall conversion rate and profitability of your campaign. So if you do a fantastic job of pre-selling and that bounces a lot of traffic, but the balance converts that might be a better page than a really generic page that induces lots of click throughs, but yields almost no conversions.