Gold-plated cables and the other things you can leave on the shelf

The pitch lands when you're least likely to push back. You've just spent serious money on a phone, a TV or a laptop. Then a clerk, or a checkout page with a "frequently bought together" row, offers a cable, a glass protector or a protection plan that looks tiny next to the total. That's the design. A few of these are fine. Most are profit dressed up as caution.

Gold-plated "premium" cables

What it promises: a sharper picture, faster charging, a cable that lasts forever.

Why skip it: HDMI carries a digital signal. The bits arrive or they don't. A pricier cable doesn't paint a prettier picture. Gold plating is on the connector tips, where it resists corrosion, and that's a small thing to charge extra for. What decides whether a cable works is the spec it's built to.

Do this instead: Buy by the spec on the box. For HDMI at 4K with high frame rates, look for the certified Ultra High Speed label. The HDMI Licensing Administrator runs that program, and the label can be scanned to verify. For USB-C, check the stated charging wattage and data speed against what your device needs. Two USB-C cables can look identical and behave very differently.

When it's worth it: When the spec is the point. A laptop that wants a high-wattage charger needs a cable rated for it. A long run behind a wall is another case. Pulling a cable back out of drywall costs more than the cable ever did.

Cat8 and "gaming" Ethernet cables

What it promises: future-proof speed and fewer lag spikes.

Why skip it: Your speed is capped by your internet plan and the ports on your router, not by a cable that outclasses both. Most home runs don't need exotic cable. Check what your plan and router actually deliver before you pay for headroom you can't use. The numbers that matter are in the home internet numbers that matter, and the ones that don't.

Do this instead: A plain, solid Ethernet cable of the right length, from a maker that prints its category on the jacket. Keep it short and untangled.

When it's worth it: If you're wiring a house and running cable through walls, the labor is the expensive part. Spending a little more on the cable itself, so you only do the job once, is reasonable.

Screen protector bundles

What it promises: three glass protectors, an alignment tray and a wipe kit, so your screen never gets a scratch.

Why skip it: Most protectors fight scratches. They won't save you from a drop onto a corner. Check what your phone maker says about its own glass before you assume it needs help. Meanwhile, a three-pack gives you three chances to trap a dust speck under the film. What kills screens is a hard fall, and a case with a raised lip around the screen does more about that than a sheet of glass does. Keep keys and loose change in a different pocket and you've handled most of the scratch risk for free. If you want the full approach to making a phone outlast the contract, read make your next phone last five years.

Do this instead: A decent case with a lip. Clean the screen with a soft cloth.

When it's worth it: If the phone lives in a pocket with sawdust, sand or metal shavings, one good protector is cheap insurance. Ask the store whether installation is included. Fitting it right beats doing it on the kitchen table.

"Military-grade" rugged cases

What it promises: drop-proof protection that soldiers would trust.

Why skip it: The phrase usually points to a drop test the maker ran itself. The label doesn't tell you the height, the number of drops or the surface. Treat it as a slogan until the maker gives you those numbers.

Do this instead: Look for a case that publishes its test details, has thick corners, and sits proud of the screen and the camera. If it doesn't say how it was tested, assume the box is doing the talking.

When it's worth it: If you work on concrete, climb ladders or live in a truck cab, a bulky case earns its bulk. Carry the heavy one on purpose.

Extended warranties and protection plans

What it promises: peace of mind for two or three more years.

Why skip it: The product already ships with a manufacturer's warranty. Your credit card may extend it, and the benefits guide will tell you how. The plan is often a margin line for the seller. Say a plan costs $200 on an $800 gadget. That's an example, not a quote. If you set that $200 aside in a repair fund instead, the money stays yours when nothing breaks. Over several gadgets, that adds up.

Do this instead: Read the manufacturer's actual warranty document. Check what your card's benefits cover. Then put the plan money in a savings account marked "repairs."

When it's worth it: A phone plan can make sense if you're hard on phones and a screen or board repair would hurt. Before you sign, read for the deductible, what counts as covered damage, whether theft and loss are included, whether you have to register, and who pays shipping.

Paid setup and security suites

What it promises: "We'll move your data and lock down your device," for a fee or a yearly subscription.

Why skip it: Phone makers include free transfer tools. Computers ship with built-in security tools, and Windows Security on Windows is one example. The real risks are reused passwords and accounts with no second step. A subscription doesn't fix those. An evening of your own time does, and lock down every account you own in one evening walks you through it.

Do this instead: Install the updates. Use a password manager. Turn on two-step sign-in everywhere that offers it.

When it's worth it: Handing a parent's old computer to a professional is a fair expense. So is a heavy TV on a wall you can't confidently find studs in. Some jobs are worth paying for, and a bad one costs more than the fee.

How to say no at the counter

The clerk is doing a job and probably has a quota. You can be kind and still not move.

• "No thanks, I'm all set." Then stop talking. Silence does the rest.
• "I'll check what my card already covers and come back if I need it."
• "I'd like to read the warranty first. Can I take a copy?"

If they push, say the same line again, pleasantly. Say it a third time if you have to. The clerk has a quota. You have a budget. Be courteous about it, and keep the budget.