You can make fun on Donald Trump's hair or criticize a product from the consumer end (the cable company example) after signing non-disparagement. What it cover

You can make fun on Donald Trump's hair or criticize a product from the consumer end (the cable company example) after signing non-disparagement. What it covers is what you say about the company in the context (which can be broadly defined) of your being an ex-employee. If you say, "I worked at Time Warner Cable and it was run by idiots", that violates nondisparagement, because you're saying it as an insider. If you criticize the product not under your real name, or in private while not representing yourself as an ex-employee, you're probably fine.