WHAT.
Oh maybe it was some hard dry snack for the dog and if the dog liked it, it’s okay I suppose 
The dog surely would like it without all that time but if it was for chewing it for long…
I won’t try to cook liver for hours in the oven, no idea if it would smell though I never ever had bad smell from a good food item until I got a seriously burnt smell… So I chalk it up to human differences. Or maybe that liver wasn’t like the liver I buy, who knows? Or the oven had some old organic matter inside…
You aren’t the first one being like this with organ meat I met… It’s so strange to me though. I grew up eating liver, of course but if you are curious, why not to try it? It’s easy and it’s obviously a food to eat, so many of us do it No one forces you to eat it all if you don’t like 
And there are methods against the strong flavor, I always write about mixing it with meat, that helped me when I found my chicken liver too strong flavored… I do like the liver flavor but sometimes I want a bit less of it. Originally sweet onions helped with the bitterness and they diluted the flavor a bit too, of course there were side dishes too… But I still eat it with eggs quite often… Or some other meat… Just fried chicken liver all alone, I accept that may be an acquired taste or not even that for many 
Oh and if you dislike it, it doesn’t mean you dislike all liver. It’s the organ (among the few I actually eat) that has the biggest variety among species according to my tastebuds and other senses. And the specimen may matter too, I tried to cook pork liver 2 times and I disliked it once and very much liked the other time. (Maybe I did something different too but to that extent?!) Similar with beef liver but I liked it first and not so much for the second time.
Not that funny, I dislike even certain cuts and love other cuts I probably could eat all though. I just don’t even try it with the leanest ones… Organs are another world and liver is very unique! No wonder that we react differently to their smell too.
If you are hesitant with organs in general, try something else instead. I consider heart safer Chewy but that’s part of the charm And tongues are the best. I have 4 now (pork), freshly cooked (well more than 5 hours ago but it took its sweet time to cool down, I should put it into the freezer now, good I remembered). One can even choose which part they want to taste first, the lean tip or the wonderfully fatty back part I share it with my SO, he likes leaner meat, I like fattier meat (our tastes interlap), it works wonderfully…
Oh, organs. Wonderful things. My life would be so much poorer without them. I just wish I could get blood 
That’s tasty! And toxic in bigger amounts but I don’t know why, I just met this info a few times.
I ate fried blood only once in the last decades… I LOVED the stuff as a kid. With onions.
And while the meals happened decades apart, I think chicken and rabbit blood are similar. Never tasted any other kind (except my own, raw, obviously but raw blood is another thing entirely, not so tempting for me).
