Should an Infected Batch Stink?

I recently had a batch that turned to vinegar. That batch smelled kind of sour, even in the fermenter.

Now, I have a batch of lager that I am worried about. Two flies got into the cooled wort, I had to dip them out. Smelling the airlock, it smells like...beer. No sour smell at all.

I do have some little flecks floating on top that COULD be infection, or could just be bits of krausen. It's cold crashing now, and will be kegged later this week.

Will a batch always have a bad smell if it is infected?

The suspense is killing me!

No. But taste and smell are the best way of knowing. Taste the batch. As you've said, your previous batch tasted and smelled sour.

If it tastes and smells like beer....it probably is.

UPDATE: Kegged the batch today. Drinking a pint now. It is very green, needs at least a month of lagering, but should be very nice by my birthday.

No, some infections don't produce any smell. And some yeasts produce odd odors during a normal ferment.