Each requires a different method of scrubbing. There is very little, in most cases, that can or should be done to text input. This is a Very Bad Thing. Numeric Data Numeric data should always, always, always be converted to a number before being used in a query. A database null is often confused with a null string.
Databases work with nulls in interesting ways.
However, when a database returns a null value to ColdFusion, ColdFusion represents that value as a null string. I think the difference between a null string and a null value is subtle, but very important, and would personally recommend disabling that behavior, as a rule. I rarely see time-only fields, but I hear they're out there. Seriously, code resilience is the hallmark of the professional programmer. Include a brief comment describing the page's function and indicating which other pages link to it, and scrub all your incoming variables.