I'm from Venezuela and currently i'm looking forward to study abroad (it could be either Spain or USA) however I'm really really scared because last year i had a pretty big problem at immigration on Lisbon's airport. I was traveling to Spain and I was going to stay at a friend's house however she never said anything to me about issuing me the invitation letter and I thinking that she had to paid for this letter, didn't think it was worth the inconvenience, therefore i brought a 7 day reservation to an hotel(i was staying in spain for two months). Anyway i entered Europe through Portugal, there they asked me how much money I was bringing to my vacation, and apparently the money that i had wasn't enough.
They interrogated me for HOURS asking me all kinds of questions, asking me to describe the places where i was going to travel while I was in Europe, what were my parent's profession, etc, etc. At the end, they told me that they were going to return me to my country because what i said didn't make sense. At that point, I told them that I was going to stay at my friend's house but i didn't have an invitation letter. They contacted my friend, she sent her documents and they let me go to Spain normally. At the end, I was never denied entry to Europe.
However, I know that what happened had to stay in my passport's record and now that i'm planning to possibly study in Spain I'm really scared that they deny me the visa because of the incident. What can I do? Do you guys have any similar experiences? Can this influence in my application to a student's visa either to Spain or the US? Should I contact the immigration at the Lisbon airport and ask them whether what happened can influence my entry to other countries?