You can do some checking yourself and the internet is a good place to start. If you type the name of the company and add “scam” or “fraud” to the search, anything that has been written will show up. Keep in mind that what you are looking for usually starts showing up after the first few pages, so keep looking.
You can also go to the company in question and see where the home office is located and then call the Better Business Bureau for that area. Not all companies are members of the local BBB, but people who have complaints often want someplace to vent and will contact that local BBB.
Also, the USPTO has a page at http://www.uspto.gov/inventors/scam_prevention/index.jsp. This will help you spot actions that are questionable.
Keep in mind that if you are looking for one company to do everything for you, you are leaving yourself open for scam operators. There isn’t one “do-it-all” company. Inventing is hard work and it takes time, money and due diligence.