The broken inventory system is just the last straw for me that makes this game unplayable.
I buy a blunt from Trevor, it's in my inventory, I go smoke with Katrina, it's still in my inventory. I go buy another blunt from Trevor, now there are two separate inventory slots taken up with blunts. I tried buying a third, it tells me I already have one.
Now, go smoke with Katrina and come back, now I can buy one and my inventory looks like:
One more bottle of booze and all my inventory slots are filled.
Yes, I put a camera in the one spot a camera could go and bought a second to see if I could. I went to the store and bought whiskey and wine, now my inventory screen is full, but apparently I could still buy things. I can work around this problem by dropping things I know aren't actually there anymore, but I shouldn't have to.