One workaround:
I had added rows to a cfsearch query, and set a numeric value in custom1 field
that that query provides. A query of queries generated the "Unsupported
Numeric type conversion in Query of Queries" error. After reading somewhere
that it is because insertion of numbers into queries fails due to CF treating
them as text values, I started guessing at conversion possibilities. This works:

CFSET junk = querysetcell(myquery,"myfield","" &
my_integervariable,currentrow)

Appending the integer value to an empty string, before inserting it in query
row, seems to make a subsequent query of queries work! Bizzarre. Blows my
mind! I don't really know why!

Regards,

Damion