trix said:
This is like saying "Don't talk about knives or how sharp they are it might be used badly".
The analogy is flawed. There are basically two types of people that use packet sniffers/injectors/etc: those with ill intent, or those that are certified and paid to do the sniffing they are doing. There's also a third group of people that are just curious about stuff, but in my experience they either quickly move on to something else once their curiosity has been quelled or become one of the first two groups, so they don't really count.
In contrast, a knife is used by a lot of different people for a lot of different reasons. It can cut food, it is a weapon, it is a hammer and screwdriver, it can be decorative, it can be entertaining. It is casually used by almost everyone every day. The casual user isn't likely to use a packet sniffer.
When you're talking about a knife, the set of illegal things that people hear done with it are far eclipsed by the legal things they know happens with it. Someone asking for a knife online has a much more likely chance of just wanting something that can cut their steak than to cut their boss.
When talking about these sorts of cracking tools, the line between legal and illegal is much sharper. Combined with the notion that someone being paid to do it has likely taken a course and probably already has the tools available to them, the odds that someone asking for such a tool has malign intent in mind increases sharply, and people would be foolish not to be cautious.
A better analogy would be someone asking where they can buy bleach and ammonia online: two perfectly legal chemicals, with very normal uses, but the fact that someone wants to buy both at the same time should cause some questioning.