Plenty! First, so-called "adware" software watches your surfing habits and extracts and records information about where you've been and what you looked at, how long you look at it, and what you buy. Second, adware is a parasite. It "lives" (makes money) by selling ads to cover up sites the adware company doesn't own and doesn't buy advertising from. In essence, it sucks the life out of sites it covers up with its own ads.
The screen shot to the right shows you exactly how detrimental some of these programs are to website publishers. This screen shot was taken recently from an old computer, on which I had purposely loaded at least two or three adware programs. I can't say for sure which of the adware products made this particular ad show up on top of the Business Know-How website, but it was one of them. (I've purposely blurred out the advertiser name and the offer to avoid indirectly promoting the advertiser who paid the adware company to display their ads on top of other company's sites.)
As you can see, the adware ad covers half of our home page. It prevents the visitor from seeing half of our top menu, a good chunk of one of our advertiser's top banners, all of our left navigational menu, and most of the text in the center of the page!
Here's yet another spyware program in action. This one changes the ads that are on our page and substitutes ads with other people's ads. Each of the ads circled in purple are ads that have been substituted for ads from our advertierser and sponsors! These are ads for things we have not approved, get no money from, and in several cases would never run on our site. One of the substituted ads even claims to be for a program that stops spyware!
If you see ads that look like these on Business Know-How pages please do NOT patronize these companies. In my mind, what they are doing amounts to theft of services and trademark infringement. They are using our good name to sell their products and covering up ads from our advertisers with ads we get no benefit from.
Off-line, that would be considered vandalism. Imagine, for comparison, that you own a store in town or have a shop in the mall. When you went to work one morning, you find someone had covered most of your display window with a big sign advertising products someone else sells. And worse, there's no way to remove that sign, unless whoever put it there decides on their own to take it down.
So, even if you don't personally mind having a program on your computer that spies on where you go on the web, reads information from your hard disk and uses that information for its own personal gain, consider what adware does to the websites of hard-working small business owners like you. Oh, and don't forget that what the adware does to your ability to surf the net. In addition to displaying annoying popups and unders on sites you visit, they can sometimes display so many popups that they eat up systems resources and crash some computers.
I hope if you consider the points made above, you'll remove whatever adware might be on your own computer.
The ad below points to a software product that will scan your computer for free and let you know if there is any adware (spyware) on it. If you do have adware on your computer, and if you want to use this particular product to get rid of it, you can buy the product for a small fee.