This may seem silly, but if I bring these generic 3 oz bottles you can buy for .99 at the store and fill one with rubbing alcohol, another with hair conditioner, etc. is security going to ask what is in them if they are not labeled?

No they don't.

You might want to put some vodka in one for a good flight.

Nope. They won't care (though I do label mine since some of my liquid products look similar in color).

You just take the ziplock out of your carry-on so it is visible, when you put everything in the bin that goes on the conveyor belt thru the xray machine.

I haven't taken my ziploc bag out of my carry-on in the last 10 or so times though security and body has batted an eyelash.

Others' experience may vary.

Nope, they don't care and they don't ask.

I find that I'm more likely to be asked (or expected) to take my toiletries ziploc out of my carry-on at smaller airports, possibly because they're just not as busy.

Do make sure that the generic bottles are really 30 oz or smaller---until recently a lot of travel-size toiletry bottles were manafactured in 4 oz sizes.

Usually they don't...actually they often don't check for anything. The one time they took a liquid out (I forgot I left an icepack in a very small cooler that I threw in my carryon) the tsa agent that took out the icepak took it out of the cooler - while ignoring the scissors I forgot I left in my bag that were right next to the cooler.

they fuss over the computer, and other glaringly obvious stuff, but they have never bothered me, a middle aged woman (ouch! that hurts!!) traveling with family about anything under the top layer in my bag.

just curious why do you bring so much rubbing alcohol?

J62~ This was a very recent trip & I hadn't taken my cosmetic bag out of my pocketbook, it had eye drops and liquid concealer inside... the TSA guy scolded me. Said no problem BUT they needed to "be visible" to him and please pull it out next time.

I use those same bottles and have traveled many places in US and abroad with them. I have never been asked what they are but I have been asked to rub a small portion on my hand from a generic bottle. It happened on a domestic flight between two cities in a European country. Guess the bad guys wouldn't be smart enough to empty a brand name bottle and put in bad stuff instead.

I re-use all kinds of plastic bottles, including those orange prescription pill bottles for shampoo, lotions, whatever.

Maybe you want to put some labels on for yourself, not to confuse shampoo and conditioner, for example.