As part of a bulk load of data from an external source the stageing table is defined with varchar(max) columns. The idea being that each column will be able to hold whateve
The storage overhead is the same between varchar(n) and varchar(max) The storage size is the actual length of data entered + 2 bytes
MSDN Reference
Check out these similar SO questions:
https://stackoverflow.com/questions/166371/varcharmax-versus-varcharn-in-ms-sql-server Are there any disadvantages to always using nvarchar(MAX)?