A funny way of looking at it is described in a book I bought, very old 'Starting electronics' (25p local carboot, ten years ago and it was old even then).
I don't know if it'l ring with those in the know but it describes it like this:
'if you think about it, negative flow in one direction is the same as positive flow in the other'
An alternative look at it:
Conventional Current vs. Electron Flow
On my travels to find a really good definition, it seems this is one of those wacky things in electronics, where a mistake was made and it was easier to not fix, which is why we get the confusion between electron current and conventional current.
If you fancy more reading:
Conventional vs Electron Flow
The way I see it, if you put a shopping bag on a set of weighing scales that weights 20kg, then take away a bag of sugar weighing 1kg...
So what have you done, have you added -1kg or have you just removed 1kg?
As you see, it actually makes no difference, just alters the way you look at it. Current flow is current flow, but circuits generally work with conventional flow, i.e positive to negative, as they originally thought it did.