Another stupid newb question:
Believe me, if any question can be considered a 'stupid newb question' it certainly is not this one. It's an excellent question and will elicit important replies from both sides of the fence.
it always seems that most people record dry or raw tracks, then add effects later, but I've always wondered why this is the case. What is the disadvantage of using, say, an external flanger or overdrive pedal and plugging into a multi-track and recording it that way vs. adding the effects later?
RAMI, Bobbsy and Armistice have concisely and effectively {
no pun intended !} pointed out the two main sides. And I'm on both sides.
I remember in the past recording with excessive reverb on vocals or other instruments for that matter. And the take would be just right, just how I'd want it. And then time would elapse {often years} and when I came to mix, I'd find I had a cavernous mess that was nigh on impossible to fix because I and my tastes maybe altered somewhat and my ear would have developed/progressed. And I'd be stuck. So it turned out that alot of my early stuff was making the best of a right mess because I couldn't change anything and re-recording was rarely an option, with people having emigrated and stuff. So most of the time I'll record dry and add after.
On the other hand, there are some instruments like guitar and mandolin {the electric variety} where I'll record with the effect because the effect is crucial in the making of the particular sound I want. It encourages me to make decisions very early on and stick with them and indeed, tune all that is added to the song thereafter to the range of effected sounds that exist up to that point.
I find it interesting that many vocalists like a certain amount of reverb in their headphones while they record even though the 'verb isn't being recorded. I find it odd.
One other thing about recording the effect - it's a great way of learning how to avoid overkill. Far better to have too little permanently on in case you do change your mind than too much.