Not all plastics are created equal.
Not all plastics are recyclable.
Know the items, not the materials.

Just focus on the shape, not the type of plastic
When deciding if you should put plastic into your recycling, the size and shape are more important than the number on the bottom of the plastic. Recycling sorting machines are designed to expect certain sized and shaped plastics, not the specific material type. Clark County recycling accepts plastic bottles, tubs, jugs and jars.
Why?
The Material Recovery Facility (MRF) that sorts recycling is designed to recognize objects; the MRF is not designed to be able to identify the material an object is made from. Because of that, objects that are not accepted can cause havoc on the machines and shut down the recycling process. Some of these items are recyclable elsewhere, but since they were improperly placed in a curbside recycling cart they now will end up at the landfill, or contaminate good recyclables causing them to go to the landfill too. A common problem plastic is plastic bags, which should never go in your home recycling. Do your part, and recycle right.
Plastics numbers (resin codes)
Did you know it is State law for plastic products to have a resin code? The ASTM International Resin Identification Coding System (RIC) was originally developed by SPI: The Plastics Industry Trade Association (SPI) in 1988 to identify the plastic resin used to make a product. This was helpful for manufacturers, but was never meant for consumers or residents for recycling. Commonly seen as a triangular symbol made of chasing arrows with a number in the center, the resin code is often confused with the recycling symbol. In 2013, SPI announced that resin codes will start to use a solid equilateral triangle (without the arrows), with a number still in the center, to eliminate this common mix-up with the public.