I LOVE these guys. They had so much character and their designs were great. They actually looked like those people that would try to sell you a "cure-all medicine" or something like that. On top of that, I love steampunk styled things, and the Super Squeezy Cider Squeezy 6000 is one of the coolest looking machines in a cartoon show EVER. There was something about Flim and Flam that didn't make them total villains, and that was great. The fact that they're brothers is pretty freaking awesome as well, the bro-mance is strong with those ponies. Oh, and: BEST MLP SONG EVER. Just look at their animation, and listen to their amazing singing voices, both of them in sync with one another. Applejack may be my favourite mane six pony, but these guys are my favourite ponies in the whole of Equestria.
I never thought of them as being malicious. Every traveling salesman, especially those of the late 19th century (Flim and Flam are based off of them) had to be competitive in order to make money. Sure they came across strong, but they were supposed to. Confidence sells, after all. They even offered the Apple family a partnership. Of course the profit split was ridiculous, that's how you start bargaining. They probably expected them to make a counter-offer, not flat out refuse. And they were never anything but polite. Again, traveling salesponies. Take it from someone who knows how to work people, these guys are just doing their level best to survive. If they were malicious, they would have been doing a whole lot more than they did.
It may have been mentioned already but I only have three words and two quotation marks. "The Music Man"
