In U.S., Socialist Presidential Candidates Least Appealing

[Mercenary]

Well I wouldn't vote for an actual socialist either.
Sanders though is just a left liberal, not a socialist. I find it a little odd though how someone would actually use the label to describe themselves when they aren't really socialist. Unless he is actually
 socialist and just realizes it isn't practical and settles for being a left liberal.

[Mercenary]

Economic freedom is certainly a concept.
You are either free to engage in economic activities as you like or you are restricted from doing so.
Low economic freedom would be not having control over your money or purchases. An economy that is centrally planned to the extent that all items are allocated through planning rather than individuals freely choosing what they wish to purchase would be an example of such. Ultimately the economic freedom in the US and in 1st world countries in general is quite high. It isn't just about how high your taxes are.

Socialism I think is fine on a small local scale in a voluntary manner. I do not think full blown socialism could work with a country as large or diverse as the U.S. However, greater economic planning could work if done right just as less central economic planning could work. There isn't only one solution that works. Some solutions will work and some wont, but among the ones that do work some may be at odds with each other.

Also someone calling themselves socialist is different than being called socialist by a bunch of tea party types. It will stick more with someone like Sanders than it did with Obama. Words matter to people. Even if the policies are the same, one person could win because how they present the policies and one person could lose in a landslide. I don't think Sanders suggestions are socialism, they are just more economic planning. I don't even think his suggestions necessarily lead to less economic freedom.

Neither capitalism or socialism are right or wrong, they just are. I think both can work, but generally it is a combination of the two that tends to work best.