If you contaminated it prior to fermenting things to look for at bottling would be foul smelling floaties with a hairy texture, a general foul smell etc.
In the Bottles, Your first clue will be floating or clumpy sediment instead of normal bottom sediment. The second would be nasty smell when you pop one, the third would be spraying the first taste accross the room and running for something to rinse your mouth with (or it could just be a grimace and spit).
Relax
Homebrew is forgiving, especially at bottling time since it has limited fermentable sugars left and alcohol content. And if you had contaminated it prior to bottling you'd probably know it already
What exactly did you do that was unsanitary?