If saving time figuring out what something is can be seen as a good thing, then this concept extends regardless of length. An attempt should be made to make it short, but when in doubt, don’t make it too short.

“Everything should be made as simple as possible, but not simpler.” – Albert Einstein

do you already see an inconsistency?:D

a little tip:
5. Use positive logic for your variable names instead of negative logic.

In that case, I’d prefer to declare only the int variable, for the QueryString won’t be modified among these lines, or to use more descriptive names:

int customerId;
int.TryParse(Request.QueryString["cid"], out customerId);