Out of curiosity, I tried

select * from mylogins 
where logintime like '2013-08-06 17:51:18'

and a few other combinations, with % in some places. No error, no result.

Too bad - SQL server throws errors for all kinds of funny reasons, yet this goes by silently. And it could actually be useful for partial date search - when you know only the decade and month, or some other parts of the date. It's silly to use plain strings as date literals in the first place, and then even sillier to never fix the statement parser to not allow this. Yes, the argument to compare with is a string literal, but that doesn't mean that all operators that apply to strings make sense.