Download bots are a well-known secret of the iOS eco-system 14 years ago
It's not really hearsay. The top CEO quoted runs a company, Fiksu, that does user acquisition on behalf of Groupon, Gilt, Vh1, etc. Most large developers know about bots because they've used or tried them.
They will say this off the record to reporters, but never on the record because they don't want to be banned by Apple.
Also, Apple issued a warning to developers about using these services last week.
Also: @Alexlin, who everyone is beating on in the comments, ran a user acquisition, marketing company for apps called G6Pay and runs his own mobile gaming company, which is part of YC. He actually knows his stuff about how to get to the top of the charts.