In regards to the highly expensive XJ rasin cakes sold on wheeled carts back in the days.

Some of the sellers' method of solicitation were deemed scams. Rumor has it they cut large chunks and would pressure unsuspecting buyers to pay in full. If cut, you buy. Over 100RMB for a piece was not unusual.

Bad word of mouth got out, but I always wanted to buy their rasins to try if not for the hearsay intimidation factor. Perhaps another day.

What did they taste like, has anyone tried?

With those cakes the trick was to say "I want ....rmbs worth". They were lovely those things.

The fruit and nut 'cake' that I remember was like a big granola slab, about 1m square and 10cm deep. It was really delicious, if you are into that sort of thing, but one never knew how hygienic preparation areas were.

It is always possible that the price of fruit and nuts has increased so much in recent years, and even the smallest farmers in the remotest of areas are selling to all of China on Taobao now, and can get a better price. There may not be any cheap raw ingredients available anymore.
Yes, often street vendors did cut off more than you wanted, but then they try to do something similar in the wet markets too. Another trick is to tell them where to put the knife, if they don't want to do that, walk away.
If anyone ever tries to play the 'if it is cut you buy', walk away. If they kick off, keep walking.

At Aegean Mall (Bailong Road) 5th floor across from ice skating rink sits a fancy xj restaurant called 北疆饭店. Both restaurant ambience and waiters are adorned with local custom decorations. A kebab grilling and flatbread baking section is visible behind transparent glass. They are also participating in this weekend 50% event.