I think you should judge SICP on what the authors' own intentions were, not on things they weren't trying to do. I didn't get the feeling that cleanness was emphasized or encouraged (any more than in any class). There are other classes that cover fundamental algorithms like sorting, SICP isn't about that.

You might find the authors own critique of SICP interesting:

https://news.ycombinator.com/item?id=34657535