This is the complaint most likely to end with no fault found, and understanding why saves you a service call. Many modern dishwashers, Whirlpool included, dry mainly by condensation: the load is heated during the final rinse, then moisture leaves the hot dishes and condenses on the cooler stainless tub wall, where it drains away. Nothing blows hot air across the load.
Why Plastics Stay Wet
Condensation drying works on items that hold heat. Glass, ceramic and stainless steel come out dry because they store enough heat to evaporate the film on them. Plastic holds almost no heat, so it cools instantly and keeps its droplets. A load where the glasses are dry and the plastic containers are beaded with water is the system working as designed, not a failure.
What Actually Improves Drying
- Use rinse aid, and keep the dispenser filled. This matters more than any other single thing. Rinse aid breaks the surface tension so water sheets off instead of beading. Many owners who report poor drying have an empty dispenser.
- Turn the rinse aid setting up if your model allows it and items are still spotting.
- Select the heated dry or extended dry option if your model has one. Eco cycles usually shorten or skip it.
- Load so water can run off. Angle bowls and cups so they do not cradle a puddle, and keep items from nesting against each other.
- Put plastics on the top rack and accept they will finish damp.
- Crack the door open at the end and give it fifteen minutes before unloading. Steam escapes and residual heat finishes the job.
- Unload bottom rack first so water trapped in upturned items does not rain onto dry dishes below.
When It Is Worth a Look
If everything comes out soaking including glass and china, if the interior is cold at the end of the cycle, or if drying used to be fine and suddenly is not, then something has changed: the heating element, a thermostat, the vent flap or the control. That is different from plastics being damp, and it is worth booking a Whirlpool dishwasher repair visit. Mention whether the tub is warm when the cycle ends, because that single fact splits the diagnosis.