[WARNING!! You are now entering rant territory...]
The most frustrating aspect of Egypt is how everyone is out to scam you. I'm sure you're thinking "Now, David, you're exaggerating..." - I'm not. Of every ten remarkable (non-neutral, i.e. people you remember) people I meet, five are merely annoying, perhaps three frustrating, and one downright upsetting. There are so many scammers that by the time you're just getting over the last one, a new one comes along. Granted, there's one actually nice person in the crowd, but even the nice people are no nicer than anywhere else (and the not-so-nice are much more not-so-nice than elsewhere). Likewise, even the supposedly nice people often turn out to scam you in the end. Basically, the scale tips well into negative territory. To be fair, my cultural background dictates what I find to be "neutral", and neutral in my eyes is "nice" in Egyptian terms, but that doesn't change the stats.
The man in this picture falls in the "annoying" category: his scam is that he stands in front of all your pictures and asks you to take pictures of him, and then when you do he tries to charge you for the privilege. I took his picture, but did not pay.
The next category is "frustrating", as they create situations in which you are annoyed even though they don't stand a chance of profiting. I mean, I can understand someone trying to make a buck when times are tough. And I can tolerate some amount of proactive marketing on the street: it is theoretically possible that I would like to rent a felucca if I'm walking along the Nile. But when you say "no" thirty times in a row while walking in the opposite direction, pleading with them to go away, that's just frustrating harassment. Luckily I learned towards the end of the trip that a simple yet forceful "I will not give you money, please go away" does the trick in all but the most extreme cases.
However, there are many extreme cases where you're just trapped in an endless and pointless cycle of annoyance. My final taxi ride, for example. I wanted to go to the harbor. I was told not to pay more than five Egyptian pounds (I've taken to asking local people that I trust, or that at least wouldn't stand to profit by screwing me, whenever I can). As I was getting in I asked how much, and he said five pounds. Perfect. Next we started a conversation, in fluent English, about the World Cup. I explained I was American and happy our team was doing so well. Suddenly his English skills evaporated and he started to say, in broken English, "Five dollars." I repeated that it was five pounds (roughly one dollar), and he started yelling at me "No problem, no problem. Five dollars. There is no problem." I said, "No, it's five pounds, or let me out of the taxi." Again I was berated by a stream of confusing and broken English, most of which was to the effect that the price was in US dollars. I inadvertently blurted out that I only had ten Egyptian pounds, and no US dollars, and he started saying "Ok, ten pounds." At this point I said "Screw this, let me out." At this he got offended and pouty. End of Act I, on to Act II. Next he started with the outright begging. "Ok, five pounds... And one dollar? [no] Five dollars? [no] You give me one dollar tip? [no] One dollar baksheesh? [no]" This continued, without pause or interruption, for the remainder of the trip. Literally, as I was getting out the door, he was still yelling, in a strangely petulant yet demanding tone, for one dollar. I just walked away. Damn, I hate situations like that. I didn't even have a dollar, and he would have had a much better shot at my last five pounds had he just continued talking about the World Cup.
Anyway, what I learned is that to enjoy Egypt you need to pretend you're in Disneyland, and that everyone there is an actor, and that you only talk with the actors when you too want to act. At all other times, you're a stone-faced bastard that lives in his own private world. Seeing as how I don't like either choice, I didn't care for the experience as a whole