I wouldn't mix the two.

I wouldn't mix the two. I would expect the BS to collect a bunch of the graphite until the BS is no longer sticky but slippery, and therefore useless. One or the other. If you've already graphited your rails, don't  play with the snot.

Why bother?

It is proven that graphite works. Why bother with anything else. Just clean your track, wheels, etc. thoroughly. Apply graphite lightly and "Tha's All Folks!"

My opinion about BullFrog Snot

My opinion about BullFrog Snot is that is sounds like a great product IF it went on in a smooth continuous layer and each layer was exactly like the last. But it never works like that. I have several friends that wasted money on the stuff. Great idea in theory but sucks in practical application. I can achieve the same results with rubber cement. Just my opinion.Maybe my friends and I are just to stupid to know how to make it work.

Both Together

The reason I would have considering using both on my layout is that I purchased some Bullfrog snot, first, awhile back to eventually help with my steam engine pulling capabilities.....traction assistance. I have sense embarked on some alternative ideas for improving the steam engine's pulling capabilities. 

Graphite does NOT assist in better traction, in fact it lessens it. Graphite is for electrical conductivity and preventing some of micro-arcing.

I nixed out the idea of using both together when I though about how the BFS might pick-up the graphite off the rails.

I doubt if BFS would pick up graphite that was applied right.

The question that I would have about it is how good is BFS at conducting electricity?  Does anyone have drive wheels on a locomotive that does not need to be a conductor?  Will the BFS transfer from one wheel to another and affect your electrical pick up negatively that way?

You've applied the graphite wrong if that happens

If that happens, then you've applied the graphite wrong. You apply the graphite VERY LIGHTLY (one swipe with moderate pressure) to the INSIDE railhead by tilting the graphite stick and holding it against the inside upper railhead. It will seem like you've not done much of anything with just one quick swipe and you will not see any graphite if you do it correctly with just a single quick pass of moderate pressure.

You apply Bullfrog Snot to the wheel tread, which contacts the TOP of the railhead.

If the Bullfrog snot picks up any graphite on the wheel tread, you've applied the graphite in the wrong location on the rail and you've also applied TOO MUCH.

That is incorrect if you have applied the graphite correctly to the upper inside railhead ONLY with a single quick swipe of moderate pressure. DO NOT rub the graphite stick back and forth, and if you can see any graphite, you've way over applied it.

DO NOT apply graphite to the top railhead or you will be sorry because that will most definitely reduce traction. You're applying the graphite wrong if you get any on the top railhead.

Absolute total agreement

With JoeF. He and I have been saying this for quite a while now. "Just a little dab'l do ya!". If you can see the graphite, you've put too much on!

Run trains...

...and, if for whatever reason, you've over-applied the graphite, running trains over the affected area will rapidly redistribute and "thin out" the graphite to the appropriate amount...

(Just have to do a few circuits of the main, and ignore the intuitive "if it's slipping, that's bad" thought for the moment...

...if there's too-much/enough graphite to slip, then that same "excess" graphite is protecting the wheels from "excess/slipping wear" damage. Once the graphite "thins down", adhesion will be restored and the wheels will stop slipping in consequence...   )

Happy Modelling,

Aim to apply graphite appropriately,

Prof K

PS have seen exactly this "no graphite --> too-much graphite --> run trains = just-right graphite" sequence play out on an On3 layout with 4% grades over a 30 minute period of an Open House... it was both instructional and engaging to watch the "change in adhesion over time" behaviour as the train orbiting the Main hit the "Grade up the Big Hill"...