Experience has given me trust issues!
Seriously, I forgot nothing and my distrust of others runs deep.
Age 8 a girl in class who was notorious for copying work looked at my poem then started writing, she read her poem out and got praised for the one line she stole off me.
A girl in secondary school badgered me for ages into sanding her small wooden sculpture in woodwork class, eventually I gave in and did it, only for her to get praised.
I remember an art site years back that would host competitions, they would offer a theme, you would have to post your work publicly and earn votes. Atleast twice a much better artist would ripoff my work, there was no way around it.
I'm a pushover in general, when people ask questions and express an interest in something I'm familiar in, I always find myself offering up too much information, not realising at the time that they're taking advantage.
Two former employers run with my ideas; one chatted with me in private wanting to hear 'ideas' regarding promotion in any and all areas, he applied everything I said and even had a staff briefing repeating word for word what I told him, down to terminology. The other (who had a habit of hiring and firing low paid staff, had his mother working there for free, who couldn't understand why 2 out of 3 essential, well paid staff walked out on him) applied my ideas of web design and promotion almost immediately after he "called it a day" on my job, the last day of work I thouraghly cleaned the premises alone, I was a receptionist.
My point being, I'll always think of where the wariness comes from, what questions to ask in the future and how could I protect myself.