Most of the time, yes. But make sure there are also no batteries, even backup batteries can harm the device and possible even give you a little shock. If you are going to be dealing with anything pricey, such as computers, you might want to keep static electricity in mind, and try to prevent it. It may not seem like a little static shock can do anything, but so many electric components in computers are very sensitive, so even if you don't feel it, the component might.
The last rule to keep in mind, is don't try to open something they are really trying to keep you out of. Sometimes, it might be harmless, but it is not worth the risk. I once tried to open up an old AC adapter to my laptop, but I gave up because I found out that underneath the plastic, there was about a 1/4" piece of steel surrounding the whole thing. I don't know if that is just so that the transformer doesn't get hurt, but I don't think I really want to open it up any further just to find out there was something radio active inside. (OK, so it probably wouldn't be that bad, but there is something they don't want you to get to for whatever reason.)
Oh, and one last thing, stay away from monitors, TVs, LCD screens, etc, as most of them may contain mercury or other poisons. Look over the electronic every step of the way to look for labels that might keep you from growing a third arm.