At times it can be pretty obvious when something should be a J-1 Intern or Trainee program, and at other times it is completely ambiguous.
An internship program is usually easier to spot. For example, when you have a program that would qualify as an internship (no matter who is selected) and you happen to fill the role with a foreign national, then you would likely opt to pursue the J-1 visa. Just like a typical internship, it should have specific skill development objectives as well as a structured plan to meet those objectives through on-the-job training. The program usually falls in the summer when the candidate has a break from university.
A J-1 trainee program can be somewhat harder to pinpoint. Some of the strongest training programs are the rotational programs run by many multinationals. The candidates are still in the early stages of their career with the company and have a very specific training plan that was created to give them a well-rounded skill set and understanding of the company while preparing them for a permanent position outside the U.S. Another example of a strong J-1 trainee program, is when a domestic company is planning a global expansion and would like to train a national of that country to lead the expansion abroad. The individual is brought to the U.S. for about 18 months of management training and then sent back abroad with all the tools to start up another branch.
There are more examples, but in all strong trainee programs the common theme is that there is no question that the program is temporary and that it has very specific objectives and on-the-job-training that aims to develop an individual's skill set. When I can read the training plan and see both of these things, I am usually relieved because it is an A+ application and a perfect fit for the program.
A red flag for a program that is not appropriate for the J-1 is when a company is very small and has no apparent reason to train a foreign national i.e. has no global partners, branches outside the U.S., or global initiatives. We will question if the company has enough employees to offer training (is there a manager that has the capacity to effectively train someone?) which will lead us to wonder if this is actually productive employment rather than J-1 training.
These are just a few examples but there are many other types of programs that fall in the grey area and may be perfectly good J-1 trainee or intern programs. The best way to review a program is to pass it along to a J-1 sponsor that will be able to provide specific feedback.