All those are Siamese flying foxes, not the true SAE's.
The three LFSs in my area that carry SAEs actually label them as Siamese Flying Foxes. This is as opposed to Flying Foxes, which they also carry. So although the fish in these pictures are the Flying Fox, and I'm sure have been referred to as the Siamese Flying Fox, keep in mind that these names are very confused and often interchanged. All of the SAEs I have bought the past few years were purchased under the label of Siamese Flying Fox.
I guess it's best to use scientific names. And to know what you're looking at. Fortunately it's pretty much impossible to mistake any of the three (SAE, flying fox, false SAE) for each other once you have seen them in person.
I was fortunate to get some true SAEs on my first shot. And then years later when I first saw the flying foxes, I knew immediately that they were not SAEs. It was until a few months ago that I saw my first false SAEs - in a tank where they were mixed with true ones. And you could easily spot them like a sore thumb.
And yes, they eat everything. The algae eater label is kind of a misnomer in the regard - they are actually omnivores extraordinaire. They don't require any more of a vegetable component in their diet than any other fish. So unlike otocinclus and the like, you don't have to worry about any special food for them.