Mike recently made an interesting post about how physical touch can be used to get around shields. It made me think of how else someone might try and get around magical shields and what came to mind is when someone gives you a gift, it can be the perfect opportunity to attach something to the gift that is malevolent. I can even think of a personal example.
A few years back another magician sent me a couple of rattles. I was wary about accepting them because my relationship with that person had soured, but nonetheless I did. I shouldn't have. I should have remembered instead how he'd tried to harm two people I knew, as well as trying to undermine me in a couple of other ways. I think I hoped he'd changed his ways, but knowing this person as I do, I should've known better. And by accepting his gifts, I was accepting his continued influence in my life, and also whatever he attached to those gifts.
I got rid of the two rattles a year or so later after I received them and I noticed a distinct change in my environment. I also noticed that my creativity improved. Now it could be psychosomatic, but nonetheless, just as Mike notes that physical touch can be used to get magical shields, why not also include gifts given, since if the gift is accepted, what is also accepted is what the person attaches to the gift.
I got rid of the two rattles by taking them out of my house and then burying them in the Earth, making them an offering to the land and asking that anything attached to them be recycled to the benefit of the land. And I did a banishing ritual in regards to that particular person, with the desire that he stay out of my life. I didn't feel a need to do anything else, nor a desire to.
That incident did teach me to be careful about the gifts I accept from people. While I'd like to believe that most people are motivated by a genuine desire to give something freely and with good intent, I can't help thinking of the poison apple given to Snow white. It looked good, it seemed like a wonderful gift, but one bite..,and she discovered that the gift had a bite of its own. So I accept gifts, I'd prefer to accept them from people I can genuinely trust as opposed to people who might have an alternative agenda.