For one thing, some merchants don't want people advertising their products based on their trademarked keywords. This makes sense. For instance, if someone types Nike into google, Nike wants Nike.com to come up first, not an affiliate ad. Plus, how would you feel if you ran a very large corporation, and when you typed your name into google, you got 10 results back, all nearly the same, all going to your site, 1 of them being yours, and 9 being your affiliates? It sort of gives your company a bad rep.
BUT - there are other viewpoints which are also understandable.
The merchant might want as much exposure as possible. If someone types in "mens watches" and you are Xing Watch and Gadget inc. - your ad might come up first, but what about the other 9 ads? Wouldn't you want your affiliates to take them up? Then, no matter which sponsored ad someone clicks on, then end up at your website, buying your product. Yes, you make a little less money if it's through an affiliate ad, but you also get every customer.
I think the BEST practice in this environment, is to encourage your affiliates to big on all terms (Trademarked or otherwise), but the catch being that you can't bid above the merchants price. This is quickly becoming a standard, and I think it's the best of both worlds. My opinion however.
Ultimately, it's the merchants decision. If your program doesn't mind you doing PPC Advertising, then whose business is it to call you a parasite? I wouldn't be too bothered by it.
Hannamyluv usually has not-so-nice things to say about PPC Affiliate Marketers, so I'd be interested in hearing things from her view point as well.
"parasites" drive an awful lot of sales;)
No, they don't. They leech off other people's promotional efforts instead of initiating their own traffic for the merchant. That's why they're parasites.
Definitions vary, but what a lot of affiliates mean when they talk about "parasites" is the type of outfit that downloads software onto a user's machine, then uses it to do things like overwriting other affiliate's links or popping up to intercept their traffic. They thereby steal commissions that are in fact deserved by someone else. That someone else could be another affiliate, or the merchant's own promotions which ought not to have any commission attached to them at all.
It's not parasitic if you're paying for Adwords or similar ads that drive targeted traffic to a merchant that they wouldn't otherwise have received. You're generating new value, you're not intercepting the fruits of someone else's labours.
There aren't any dictionary definitions available that I'm aware of, but there's a lot of overlap between what many people mean when they talk about "parasites" and "scumware", "adware", "thiefware", "spyware" etc.