Ads are the lifeblood for a number of sites, but when marketing becomes aggressive, they can be a nuisance for users. For some time now, their tracking capabilities have turned them into the black sheep of the Internet. To get rid of that and to increase the loading speed of webpages, Apple allowed developers to create ad blocks for Safari browsers. 

Not surprisingly, ad blockers sells are dominating the paid app section of the App Store. One notable side effect of these apps is that they are messing up the on-line shopping experience for retailers such as Walmart and Sears.

Developer of the ad blocker Crystal responded to an inquiry from Fortune and promised it would make sure the shopping sites are no longer blacklisted. However, some pages of Walmart.com still fail to load on a Safari browser that has Crystal ad blocker installed, so that posed a natural question: what other retailers are losing due to the content filtering?

The Apple store functioned impeccably, and so did Staples.com. Sears.com loaded properly, yet it popped up a survey that Crystal failed to block. Another survey passed the ad blocker's scrutiny on Macy's site. Retailing giants Amazon.com and Alibaba.com worked flawlessly, but Target refused to load individual items or the shopping cart. On the Google store, a purchase of a Nexus phone came to an abrupt stop when the cart was unreachable.

There are other content blockers that keep clients from buying on-line, too.

Purify Blocker, another top-selling app, restricts users' access to on-line shopping. Even if it offers more options, like whitelisting pages, the general effect is comparable. Amazon got a free pass, while Target and Walmart had no chance. Even more, Target would load only blank pages. Strangely enough, even after whitelisting it, the site was still unable to load. It was a relief to see that the trial of buying the Nexus device on Google store ended successfully.

Three facts should encourage developers to fix the poorly implemented ad blockers for Safari as soon as possible.

1. Online shopping numbers are increasing each month.

2. A significant portion of the e-commerce comes from Apple users.

3. The holiday season is nearly here.