There’s a controversial practice in the world of online sales that’s got some consumers crying “scam.” Those who defend the practice say it’s nothing more than honest (if aggressive) salesmanship. Like some other sales practices, it seems to tread the line between an offer and an attempt at manipulation. I’m talking about upselling.

Upselling is about as old a practice as selling itself. Customer buys something, salesperson tries to get them to buy something else while the wallet is already out. Simple, right? But in my experience, upselling can in fact be scammy and dishonest. As in so many things, it’s not a matter of whether it’s right or wrong to upsell. It’s how you go about it that determines whether or not it’s ethical.

For example, at almost every restaurant, the server will wait until you’ve reached what you think is the end of your meal, but just as the plates are cleared comes the inevitable question: Dessert? No one complains about this. Some people like dessert. Some people light up at the mere mention of it, because somehow, no matter how many times we go out to eat, we manage to forget it exists until a waiter reminds us. Some people never order it, but they’re not offended by the suggestion. The point is, nobody sees a few tantalizing descriptions of pie as an act of deceit.

Likewise, every electronics store, used car outlet, and sporting goods store upsells insurance. No one in the last 20 years has purchased a TV, used Honda, or a treadmill without being offered some kind of extended warranty. The actual value of these warranties is more than debatable, but again, no one seems to think they’re being hoodwinked. The offers are simply expected, and mostly rejected. No harm done.

So what differentiates a legitimate upsale from a predatory act? I’ve found that there are certain markers or signs that make it pretty clear that an upsell is crossing the line between selling and scamming. Once you know the signs, they’re fairly obvious. That makes it easy to avoid being scammed, and can help you be honest with yourself about your own upselling practices. There are three major red flags:

1. The upsell is necessary to use the product. If what’s being upsold is a necessary part of the original product sold, somebody isn’t playing fair. For example, while it’s not considered scammy to upsell an extended warranty on a TV, it would be foul play to “upsell” the remote. The TV can’t function, at least not fully, without it, so it should come as part of what the original price covers. An extended warranty on a car is optional. The steering wheel isn’t. Upselling dessert? Fine. Upselling a fork? Shame.

Anyone who lures customers in with the promise of a certain product being able to do a certain thing, then withholds a key component, isn’t selling. They’re holding part of someone already paid for hostage, and it’s a bad way of doing business.

2. Extreme pushiness. There is nothing more irritating when you’re at a point of sale than being harassed by repeated attempts at upselling. To be asked once if you want to apply for a store credit card is one thing. To be asked four different times if you want additional items is quite another. Online, repeated pop-ups or other obstacles placed between the customer and the checkout is not only abusive, it’s counterproductive.

The extra time a website forces a customer to spend in the checkout process doesn’t increase the odds of selling more product. It increases the odds that the customer will abandon the cart and take their business somewhere where a transaction goes according to common rules of decency. When someone checks out at the $100MBA or our sister company, Webinar Ninja, for example, it’s a one-page affair. The customer buys what they buy. We try to get them to buy more by sending a follow up email, but mostly by making sure our product is so good that they’ll want more. That’s it.

3. A lack of transparency. Whenever a business isn’t being clear about what exactly they’re selling, especially regarding what’s included in each purchase, it’s a bad sign. A common scam is for a business to include something only temporarily; somewhere in the fine print it says that the customer only gets this or that service for 3 months, after which they’re on their own. Again, if it’s a superfluous enhancement, that’s fine- but too often it’s something the customer needs in order to use the product.

Be clear about what you’re selling, and what you’re upselling. Make sure that the customer knows that what you’re offering on the side is optional, and that what you’ve already sold them is all they need- even if they decide they want something extra. Playing games with the components of your product may put customers in a position to have to give you more money in the short term, but you can be assured the resentment will catch up to you.

So in the end, should you try upselling tactics to increase sales? Personally, I don’t do it. I like to think that we earn return business by making a good product, and by keeping non-stalkery lines of communication open with our customers. That doesn’t mean it’s not possible to upsell ethically. Before you commit to doing so, the best thing to do is ask yourself how it feels. Does your gut tell you that something isn’t right? Do you have doubts that you can’t shake?

Remember that anything that doesn’t foster a business culture of honesty, transparency, and mutual benefit isn’t worth doing- even if it makes a few extra bucks. In the long run, your honesty will earn you a following that will sustain your business for years. That’s a far better investment.