Pound Signs In General Expressions - MACROMEDIA COLDFUSION 4.5-CFML LANGUAGE Reference

584 CFML Language Reference
All of the above statements result in errors. As a general rule, never put pound signs
around function arguments.

Pound signs in general expressions

Allaire recommends that pound signs be used only where necessary. The following
example demonstrates the preferred method for referencing variables.
<CFSET SomeVar=Var1 + Max(Var2, 10 * Var3) + Var4>
It is a cleaner and more efficient method.
In contrast, note the following example, which uses pound signs unnecessarily:
<CFSET #SomeVar#=#Var1# + #Max(Var2, 10 * Var3)# + #Var4#>