What I do with my new rats is first to give them a bare, open cage - that means strictly hammocks and only one or two hidey houses. This gives me access to the whole cage, and prevents me having to cause extra trauma by chasing the rats around to catch them. As soon as I get my rats, I take them out whenever I have the time for some socialization. I almost never socialize in the cage - instead, I catch the rats and put them into a travel carrier, and then I take out my smallest playpen (it only fits me sitting crossed leg and the travel cage). The only thing in this playpen is me and the carrier cage, and as soon as the rats exist the cage (or if they won't, I'll take them out), I remove it. I'll place a blanket over my legs so that if the rats want to hide, they can do so on me. I bring meat baby food into this area, and offer it on my hands to the rats. Offer any treats to the calmer and more confident rats first, as this will often cause the shyer rats to become intrigued and come out to join them.
I'll also practice picking up and immediately putting down my new rats many times a day, as I find that this is the best way to get them used to being picked up (something which is pretty unnatural if you think about it). At this point, its best to scoop from below, as picking a skittish rat up using the "claw" method (grabbing them from above) mirrors a bird catching them, and is more than likely to freak them out.
One my rats are eating baby food off my hand outside the cage, I'll begin to touch their cheeks while they eat. As they can see my hands, this doesn't scare them as much as petting them on the back (where they can't see what your doing). I then gradually move on to petting their head, then their neck, and finally their backs. Each time, they only get to keep eating the yummy baby food as long as I'm touching them. This is essentially me trying to desensitizing them to touch, and it works really well (anything paired with meat baby food has to be good in my girls minds
).
The hoody method can work quite well if your planning to go about doing chores, but even my tame girls usually won't stay inside a hoody unless I'm moving. I tend to like to use the hoody method either if I'm planning to walk around the house, or if the rats have just played a lot and have gotten quite tired, at which point they appreciate a warm, quiet place to rest. Otherwise, the only time I really use the hoody method is when I have a rat so scared that they freeze when touched. By placing them in the hoody for an hour or two, they eventually start to move around and learn to be less crazy afraid of my scent.
I doubt over handling a rat could traumatized them, as I always "over-handle" my new rats from that point of view, and that's what end up making them tolerant and tame. The one thing I'd wonder about is if your breeder was actually breeding for personality or not. Many breeders who breed for personality don't handle the pups until they reach 5 weeks of age, as if a pup is friendly and confident at this age without prior socialization, you know that that's their personality and not a behavior they just display towards you do to extensive socialization (its the whole Nurture (socialization) vs. Nature (innate personality) thing). It sounds like your boys just aren't naturally confident and bold. In that respect, it would make sense that they were friendly at the breeders (due to being extensively socialized and desensitized to the environment there) and not so friendly at your house. Rats generalize very poorly (like dogs), so if they were only exposed to one environment (and aren't naturally bold and outgoing), they aren't likely to carry the confidence that they displayed there into other places. Its like the difference between meeting a shy dog in their house, where they feel safe, and meeting them in a park, where they may have never been. Verses a confident dog, who might behave the same in both places.
As for feeding treats, I would stop feeding solid treats altogether until you're confident they won't run and eat them in hiding. Instead, switch to feeding liquid treats like meat baby food. These treats are not only super smelly and tasty for rats, but they require the rat to stay on you or next to you while they're eating. That's when you can practice touch desensitization (like I talked about 3 paragraphs ago). If you've never fed liquid treats before, you'll want to initially feed them off a metal spoon. As rats hate biting metal, they'll quickly learn to lick the wet/liquid treats. At that point you can switch to just placing the liquid treat directly onto your hand/fingers.
All my girls have come from pet shops or craigslist, so I get to see their true personality without any changes. I tame them all the same way, and they've all turned out to be great pets. It's true that some are/were always shyer than others, but even the shy ones learn to trust me fairly quickly. I'm actually working on getting one of my shyest girls to walk out onto my hand (from the cage) for free-range time right now. She's great outside the cage, has no issue being picked up, and will happily eat even large treats while I'm holding her. This is a HUGE improvement from a few weeks ago, when she peed and pooped when I touched her, squeaked like I was trying to kill her when picked up, darted nervously out of my hands, and wouldn't approach me at all. Even if you have a shy rat like Cream, it's definitely possible to socialize them to the extent that they enjoy being with you. Like I said, I'm still working with her, but her progress has been immense. I'm sure that your boys will also come along with time, and I wish you luck bonding with the little guys.
