Don't learn anything about the potential buyer

By this, I mean nothing. Don't do any research. Don't understand the target demographic. A bad salesperson will ignore the buyer's background. They won't care who they are, what they do for a living, or why they may be a buy from you. A bad salesperson won't care about their needs.

Be pushy

A bad salesperson is pushy and all they care about is closing. There's a well-known phrase in sales: "Always be closing". They even abbreviate it as ABC. But the thing is, Always Be Closing only works if you care about the buyer's problems. A bad salesperson doesn't care about the buyer's problems, they just want to sling their product.

Follow up (too) often

Bad sales people follow up often. So much that you haven't even had a chance to read their previous sales communication. To be a truly awful sales person, send an email on a Friday afternoon, then follow up again on Monday morning and inquire as to whether the prospect has had a chance to read the previous email.

Send impersonal emails

If you're trying to be bad at sales, be sure to send an impersonal email. Cold emails are inherently salesy, but they don't necessarily make you a bad sales person. To be bad, remove any personal elements about the recipient from the email. Personal touches like addressing the recipient by name have got to go. Don't ask them any questions. Don't comment on any of their background or past successes. Just launch straight into your sales pitch and you'll certainly be bad at sales. If you'd like to be really bad, be sure to BCC the recipient and address them as "Hello" or "Dear Valued Customer". These (im)personal touches are the hallmarks of a bad salesperson.

Don't negotiate

Bad sales people don't negotiate. In fact, they think their offering and price are so good that it's an insult if the buyer wants to negotiate. If you want to be bad at sales, start the conversation by saying "If your payment terms don't match XXX, then we won't be doing business together".

View your customers as cash cows

If you're looking for a good way to be bad at sales, view your customers as cash cows. That's all they are anyway. They're a bank account you debit from via profitable projects. Bad sales people lead a conversation with, "See Mr. Prospect, we're really looking to partner with customers who can give us XX millions of dollars per year in revenue." Bad sales people do this; good sales people don't. It's a great way to make your prospect feel marginalized and nonessential.

Be entirely transactional

People who buy things are, first and foremost, people. And if you buy stuff, you want to be treated like a king. Like you matter. Like you're the most important person to the seller. If you want to be bad at sales, don't do those things. Don't ask the person about their problems. Don't discuss options or pricing. Don't be flexible. Express your will and exert it onto the buyer. Make them bend to you. And above all, make everything as transactional as possible.

Smile like you (don't) mean it

Most people feel good when you smile at them. If they feel good, they tend to buy from you. A genuine, well-placed smile can do wonders for your top line. Don't make this rookie mistake. If you don't want to be good at sales, be sure to never let a Duchenne smile reveal those pearly whites. Do just the opposite. Either don't smile or fake smile; dealer's choice. Not smiling will definitely turn off a prospect, but a fake smile is even more sinister. It makes people squirm with discomfort and they'll likely recount to their colleagues about how much you looked like the Cheshire cat.