I trust Milly completely, but I do know that she has claws and teeth, and while I don't think she would ever be destructive in the house, or bite a person, I know that she is completely capable of these things. I usually plan my life around this knowledge, and don't take chances, even though I trust her.
As many of you already know, I firmly believe in crate training. Not only is this, in my opinion, the optimum way to housebreak a dog, but it also provides a safe haven for your pup. Dogs sleep in dens, they like to have their own space, and feel secure in their crate if you crate train them. A crate trained dog makes life much easier should you ever go out-of-town and have a pet sitter. If your dog is crate trained, and ever is injured and activity levels need to be limited time in the crate is ideal.
I also believe that at least as puppies it can be very helpful to keep the crate not in your bedroom. There are two reasons for this - first, you'll get more sleep... just set your alarm for some middle of the night potty breaks for a very young puppy, and secondly, keeping the crate not in your bedroom makes your puppy less dependent on you, and can help separation anxiety problems from developing.
When I got Milly she was petrified of her crate, but she has come along way, and now happily walks in when asked. I doubt she'll ever walk in it on her own (like a dog crate trained from puppyhood would), but she does not mind her time in the crate. When I am not home, Milly either is outside with access to the sun room, in her crate, or in my bedroom with the door shut, TV on, and the door leading into my bathroom closed as well. One thing I never do is leave her with free range of the house. She'd probably be fine, and not do anything naughty... okay, I know her, she'd probably jump on the sofa while I was out, and she isn't allowed on furniture. She might even get into the trash if something tasty was in it, and she's been known to do a little bit of counter surfing, especially if there is a loaf of bread on the counter. I don't want to be mad at her, and I don't want to set myself up for disappointment, so I just avoid the instances that could be potential problems. I find she is happier, and feels much more secure when left in my bedroom with all of the doors closed than she would if I left her alone with free range of the house.
When it comes to behavior in other situations, and my trust of Milly, I work very hard to have a positive relationship with her, and a lot of this comes from her feeling secure. When we go to the dog part I work on her recall (this needs a lot of work, especially when at the dog park) from the very beginning. I don't just let her play and then start calling her when I want to leave, because this is counter productive. Why would she want to listen to me calling her if I've ignored her for 45 minutes as she played? She should respond whenever I call, and she should feel secure that I am there for her. So I'll take the time and call her over every few minutes. While I want her to have fun at the dog park, I also want her to feel secure. If there was ever a fight at the dog park, or something I didn't want her near, I want her recall to be strong enough that she comes when called with distractions, and knows "leave it" if she shows interest in something I don't want her to have, or something that could be dangerous for her. I've noticed a lot of dog park conflicts come from dogs whose masters are not working on their dog's recalls, and instead are talking on their phones, reading the paper, or simply not paying attention to where their dog is, their dog's body language, and the relationship to other dogs around their dog.
I recently dog sat two toy breed dogs. The dogs had a lot of fear of new people, new dogs, new houses, and were filled with anxiety. Both were rescues, adopted together, and still had a long way to go before they felt secure. I wanted their time with me to be as positive as possible, and really worked on emphasizing their security. To meet Milly they were in their crate, and Milly was leashed on the other side of the room. Eventually Milly walked around the room, but the little dogs still were in their crate. I took them out, and they were introduced (obviously, all dogs on leashes), and things went okay, not great, but okay. When it came to them being outside I kept them in a large pen for the first three days, and let them get used to seeing Milly, and smelling her from the security of their play pen. By the time I removed the play pen the toy dogs were totally confident, and realized the play pen was their safe place, just like their crate is their safe place when inside. They were free to come and go as they pleased from the playpen, but they really seemed to enjoy having this security.
When it comes to feeding, I firmly believe in giving your dogs meals, and not free-feeding. This is my personal opinion, but I want my dog to eat on a schedule, and I'd like to know exactly how much my dog is consuming. I want her to eat when I feed her, and I practice the 15 minute rule: the bowl of food goes down at meal time for 15 minutes, if she doesn't eat it in 15 minutes the bowl is removed until the next feeding. Eventually, and usually pretty quickly, your dog will start to eat at meal times, and appreciate the structure of a schedule. If Milly needs medication in her food I want her to eat it at meal time. I really appreciate the structure of meal times, if I have to go somewhere, I know exactly how much time it will take to feed Milly. If I have to board Milly, I know that she will eat at meal times. Having a structured feeding schedule helps with your dog's overall sense of security.
In short, sometimes it's good to think about how much we trust our pets. I don't want to set my dog up for failure, and I really want her to feel safe and secure. I work hard to always be aware of her surroundings, and put her in situations where she is safe, and the amount of destruction she could cause is left to a minimum. When I introduce her to new people I always tell them the best way to pet her or approach her (especially with small children). I even practice taking her bowl away mid-feeding every few weeks. She's totally fine with this, and always has been, but I want her to know that we work on this. If ever I had to remove her food mid-feeding for a reason, I want her to not get upset or aggressive about this. If a child ever stuck their hand in her food bowl, I want her to not bite a hand.