How do near-zero interest rates limit the ability of expansionary monetary policy to work?

When the FED or any other central bank adopts a zero interest rate policy, it is usually done to stimulate the economy (expansionary monetary policy) since individuals and businesses are encouraged to spend or invest instead of saving money. Also cheap credit tends to lower the total financial cost of goods or services.

Usually economists believed there was a limit to this type of policy until the European Central Bank set the interest rate at negative values, before 0 interest rate was supposed to be lowest value possible. In this case you had to pay in order to save money which obviously was a direct pro spending policy.

But even negative interest rates couldn't produce the desired outcome since consumer confidence is negatively affected by it and the financial sector's profitability is also serious lowered. Consumer spending is by far the largest component of the GDP and when it negatively affected, the whole economy will suffer. There is also a limit on how much you can borrow and invest as a company if your revenue doesn't follow.