Are You Losing Potential Clients Because of Badly Written Emails?

One of my biggest pet peeves is getting emails from people that I don’t even know, trying to make a sale with a clearly premade template. It makes me wonder if they don’t think I’m smart enough to know that they’ve sent this same email out to thousands of people in the hopes that someone will “bite”. 
I really dislike being sold to, and so I’m very careful about how I write follow up emails because I don’t want to sound cookie-cutter or too pushy. 
I apppreciated this article that gives great tips on writing follow up emails that don’t suck:

Writing Great Follow-up Emails