I don't consider myself an expert by any means, as my experience is limited to what I've experienced with Scully, who is my first basset (and definitely NOT my last!). Here are my honest answers to your questions, and I won't sugar-coat them.....
1. Hard to train/aggressive/stubborn? -- Scully was very hard to housebreak. Eventually, with a lot of consistency and patience, she "got it". She is possibly the most stubborn beast on the planet, and although by nature, I am not a patient person, I can deal with her bassetude because I love her to death. Bassets are wonderfully natured beasties....Scully doesn't have a mean bone in her body.
2. Smell -- They sure don't smell like roses, but their "odor" shouldn't be offensive. Brush their teeth, wipe their lip pouches, keep the ears clean, feed quality food etc. are all things that will help minimize any smell. We only bathe Scully about every two months, but wipe her down with baby wipes for a quick "freshening up".
3. Shedding -- Scully sheds year-round, but more in the spring and fall. I have a Zoom-Groom for her, and try to give her a brush-down daily. But honestly, I spend a lot of time vacuuming and washing sheets/covers because of those pesky basset hairs.
4. Aggressive behavior -- That's definitely not the norm for bassets....they are so sweet. There is truth to the phrase "let sleeping dogs lie". When she was a youngun, Scully got a little testy with me twice when I tried to move her in her sleep, but I very quickly let her know that was NOT going to be tolerated and she never did it again. I don't think Scully knows the meaning of aggressive!
5. Eating everything -- I visit a few basset-related forums, and do seem to hear quite a few stories of bassets eating odd things....rocks, drywall, floorboards, etc., so I guess some of them do have that tendency. Scully, however, has never shown any interest in ingesting anything that wasn't edible. When it comes to food though, nothing can be left out because she is a pro at counter surfing! Those basset backs can stretch....far!!
6. Lazy during walks? -- Well, again, I won't lie, I have had to pick Scully up and carry her 60-pound arse home a few times. She could walk for hours in one direction, but as soon as we turn around to go home she puts on the brakes. (Perhaps I should be offended that she doesn't want to come home with me...LOL.) She occasionally will just turn her butt to me and plop herself down, and yes, it can try one's patience a bit.
7. Butt-bonding -- If you lay down the rules and don't allow the basset in bed from the get-go, butt-bonding won't be an issue I guess. Scully does sleep with us, and I have been way too up close and personal with that booty of hers. Thankfully, she's not a farter!
8. Eating poop -- Scully attempted to eat poop once while at my MIL/FIL's place, and she must not have liked it (surprise surprise) because she never tried it again. When she comes across a poop that some idiot has neglected to pick up, she looks at it, turns her head to the side and walks around it as if she's offended by it.
8. Bed time -- Scully goes to bed on her own with no coaxing. She used to wake up quite early, but grew out of that once she realized that I am the master at ignoring her when I know she's just being a pest and doesn't REALLY need to go potty at 5am. On the weekends when we sleep in later, she always wakes me up with a symphony of funny noises....not barking or howling, but noises I can't really even explain; they're just weird...LOL.
10. Drool -- Well, Scully can be a bit of a drooler, but it is mostly when there is food around, if she's been exercising, she's nervous, or she's hot. The drool puddles on the kitchen floor can be lethal....almost fell on my arse a few times because of them. She doesn't tend to sling drool on the walls...she has better aim than that and tends to hit ME instead!
11. Why I own a basset....I LOVE THEM!! Not too much more I can say. Scully is my pride and joy and for all the things I have to do for her or because of her, she returns the favor tenfold by just being her sweet self.
Good luck in your decision whether or not to become a basset slave! Bassets are not for everyone, but being a basset slave is a very rewarding and fun experience, if you can live with the potential bassetisms. Scully wormed her way into my heart, and is absolutely my pride and joy!!