Why was Scout suspected to have taken some of the Barbers' belongings in Chapter 27?''i deny having taking part in such a thing''
I do not think that anyone has said that Scout did participate in the mischief that was done to the Barbers' home. I do not see anything in the text that implies that someone accused her.
I think that what is happening here is that Scout is admitting, in a sort of humorous way, that she did have a part in it. I think that Scout is portraying this as a bit of harmless fun and that she thinks it was funny. Because of that, she is not ashamed to admit that she took part in it.
However, if people do suspect her, it is probably because she is a pretty high-spirited kid who would be likely to participate.
Please note that nothing was actually taken -- it was just moved down into the cellar.
When the unseasonable snowstorm hit Maycomb (Chapter 8), Jem and Scout's neighbor, Mr. Avery, had an explanation for it: It was the Finch children's fault.
"See what you've done?" he said. "Hasn't snowed in Maycomb since Appomattox. It's bad children like you makes the seasons change."
Scout felt unfairly charged for the natural circumstances then. When the unexplainable burglary occurred at the home of Misses Tutti and Frutti, "some wicked children" were accused of the crime. Scout wants to reiterate once again that she had nothing to do with this unforeseen act, either.