My filter for Spam is probably a bit more liberal than yours. I have to keep my eye open for people who legitimately want me to work on their websites. After all, I'm a website builder. However, it's amazing how many flavors of Spam I get to deal with each day, and it's these folks who are making my finding of clients next to impossible, partially because I'm dealing with the fake opportunities more than finding new ones.
The jerks who do this to me (and likely have almost no skills in doing anything other than annoying others) make finding potential clients nearly impossible for me. They waste my time, but they also make any email I send as a contact seem just as useless, and I have a hard time figuring out my own best marketing angles.
Based on Ads
I had to place ads. Craigslist and all the other free online places to list my company. The problem is that the ads are bait to attract folks trying to take my money, whether from the companies I listed with or with folks scouring those sites for victims. I think I've received more headaches from the listing agents themselves, but the fact is that when you list you company, someone will want to make money from your listing (instead of hiring you).
Another kind of ad I've tried using is Craigslist ads. Can you believe web design companies out of India read our local CL ads and then try to subcontract out? I've gotten several offers to let me let them build the sites I get. I guess they don't realize that it's those of us just starting out who use Craigslist.
I think Google Adwords got me one contact for the hundreds of views and dozens of clicks that were claimed as proof I was a successful advertiser. I paid like a dollar a click for about $150 worth of advertising, $100 of which was free (from Google). The one contact was a local guy who wanted to work for me. He probably thought I was making big bucks because I could afford Adwords.
Based on Domain Registrations
If you've ever registered a domain under your own name, you have been harassed by a lot of folks claiming to be web designers who can help you make it look beautiful. Most of them are sending the email illegally and are probably scammy hacks, but there's also a chance some of them know what they're doing. It's just that they shouldn't be sending emails to everyone who registers. Obviously, no legitimate American web design company would try to get away with this sort of sleazy advertising, but you'll see them. NEVER respond to them. It's like getting a ride from a Taxi driver at the airport who's holding up a sign that reads "Sucker."
Based on Reputation
My site's been around long enough and has a good enough reputation that I get contacts from those trying to scam a big company, too. They don't ignore me like in the past, so now I get to deal with people sending tricky contact emails that seem to be asking for my service but really aren't. I've gotten several recently where someone says he needs a website builder and has bought the domain. When I leave a contact number, I get an automated call the very next day from someone claiming to be with Google or whatnot. These clowns are finding legitimate businesses in order to input phone numbers into some kind of Spamming database. Super annoying, and, again, illegal. And, again, stealing potential customers from me because of their tactics.
The losers who friend me on Linkedin and then try to ask me about selling ads to Google and other big names are terribly annoying. People who have no skills to speak of and who are like carp feeding off of the bottom of the internet sludge (and probably making more than me). They are the ones who make my marketing next to impossible, but I am forced to accept their stupid connection requests because I haven't made a huge effort in making connections, and I'm hoping a contact of a contact will someday discover me. Social media is where the cream falls to the bottom and where mediocrity and instant laughs rise to the top. The whole system is almost as annoying as the people abusing all aspects of it and other means to make their careers out of smoke and mirrors. Not even. It's more like the promise of smoke and mirrors. And stupid kittens and little kids. And fake awesome moments staged by Bob Costas wannabes.
Anyhow, I'll post an example of a person spamming me. Maybe I'll keep posting them for fun, especially those with poor English.