I worked at Trader Joe's for nearly 3 years. Here are 10 things shoppers should never do there.

• I worked at Trader Joe's for almost three years, and I got annoyed by some things shoppers did.
• Forgetting to throw your trash out or put your cart back makes the employees' jobs harder.

I worked at Trader Joe's for about three years, and I learned a lot about the people who shop at the grocery chain.

Read on for the things I wish shoppers would stop doing at Trader Joe's.

Don't try to barter prices with people who have no power over them

TJ's has affordable prices, but the chain tries to source the best ingredients for its products, which can raise the costs.

The employees you meet in the store don't control those prices, so don't badger them about them.

You're not going to love every free sample, but don't complain about them

When Trader Joe's is offering samples, all the products at the demo station are given away.

If the product doesn't meet your expectations, you simply don't have to buy it. The employees can't control your taste preferences.

It's much more helpful if you throw away your trash

Whether you're at the demo station or elsewhere around the store, it's super important to pick up your trash.

Leaving empty cups and open packages is unsanitary and a nuisance to employees.

Don't blame the employees for the store's small parking lot

Some Trader Joe's parking lots can be a bit small. Unfortunately, the employees can't do anything to fix this.

To avoid a congested parking lot, try coming soon after opening in the morning.

Forgetting to put your cart back makes everyone's job harder

Leaving carts all over is a headache and wastes space in what's usually an already small lot.

There are several designated areas where you can return your cart, which helps the employees keep the space neat and safe for everyone.

If you need help with something, please ask nicely

If you want your items bagged a certain way or need help finding an item, TJ's employees are usually more than happy to help.

But please remember that they deserve basic respect. Sometimes, customers will demand things instead of asking kindly.

The cashiers are trying to keep the line moving, so be patient

No one likes a long line. But TJ's cashiers do their absolute best to assist customers in a timely fashion.

Complaining or making rude comments about the lines does nothing, especially if your own cart is packed with items.

If you have a big shopping list, don't come right before closing

Try coming in at least an hour before closing if you have a huge list.

The night crew working the last shift has to stay until every customer leaves, so coming in 10 minutes before closing can cause the employees to stay longer than they're supposed to.

If Trader Joe's has discontinued a product, there's no use arguing about it

All Trader Joe's employees have access to a database that tells them if a product is out of stock or fully discontinued.

Sometimes, one store might be out of a product, and an employee can check whether it's available at a nearby location. This happens a lot during the holiday season, so I recommend calling ahead of time to see whether a specific product is available.

But when an employee tells you a product has been discontinued, there's nothing they can do about it.

The employees aren't forced to be happy, so don't treat them like robots

TJ's employees aren't forced to always be smiling. In most stores, morale is high, and the employees enjoy working there.

But if you see someone who isn't being smiley or conversational, there's no need to point it out — they aren't robots.