Tampering with products is most often done by someone from one of the following four categories: Criminal, copycat, crazy, casual.
Criminals plan to damage, adulterate or otherwise create public concern as a method of extorting money. This can be anything from very high-profile attacks that would guarantee plenty of publicity through to low-key attacks that are done in secret, warning the brand owner of the attack so proving their capability but not allowing the adulterated product to reach the public. Criminals will usually spend time and money to make sure they produce a high-quality tampered product that is hard to detect and they have thought out how to collect on their investment.
Copycats will have read in the media about a criminal activity, and they try to copy the technique. These are usually poor imitations, and the adulterated products are more easily detected and the culprits more easily identified. This does not mean to say they have not damaged the business of the product’s producer and the retailer by their activities.
Crazies covers a whole raft of reasons that may be real or imaginary. This is often characterized as a vendetta against a company for a perceived injustice. This may be something that may to many be a trivial matter, such as a shop assistant ignoring them in favor of someone else
Casual is often a consumer who breaks a seal to look at or sample the goods without purchasing the goods. They may want to taste the food to see if they like it or not and for other goods may want to check the dimensions, fittings or connections. If they decide to purchase the item, they may discard the one they have opened and pick up one without the broken seal.
False premise of “tampering that’s evident”
Why, I imagine you are asking, do I state that tamper evidence (TE) is an illusion? I believe it is based on a false premise that someone wanting to adulterate, or in any way tamper with, a product will open the product in the way the pack was designed to be opened.
It is usual to open a bottle by removing the shrink sleeve and twisting off the cap at the top of the bottle, but a number of events where bottles, that have been found to be deliberately contaminated, have still had the caps unopened. Glass bottles have been turned upside down and been drilled through the bottom to gain access, contaminated and then the hole plugged up with a ultraviolet light cured polymer that closely matched the glass such that it was difficult to see where the entry point was made. With paperboard cartons, the lid and TE seal was left intact, and either one of the folds or overlapping seams had been opened to gain access and after tampering the access point was glued to make the pack appear intact. Examples have been found of tin cans where the top or bottom of the can has been cut off and soldered back on. This sounds as if it would be easy to see the cans had been tampered with but, in reality, with time, care and practice the results were sufficient that the items were sold, and customers opened the cans before the tampering was discovered.
In my opinion, this means that TE seals and labels only really highlight the “casual” group of miscreants where it is more of a “spur of the moment” action, and they are not investing time and money into trying to extort some return for their actions. These serious tamperers pose the bigger threat for which TE devices offer little or no defense.
Supermarkets are a common target, and if you consider that the range of products they stock would run into the thousands, and the number of customers passing through would also be in the thousands, the chances of any individual selecting a tampered product is very small. Of course, to the individual who suffers because of the tampering, it can be catastrophic.