I've been hearing a lot of stuff from a lot of different people lately.
From what I compiled, they're good because it makes the package seem a little less suspicious, and it's bad because LE can sort of connect the writing style to the dealer...
Help :(
EDIT: Main reason why I asked this is because I bought a lil' something that came with a hand-written address. It was a lil' larger than a regular sized envelope but didn't look suspicious at all...
kinda depends on the situation. a white rectangular box with a hand written return address of a bogus company paid for with stamps might look a little funny. but an envelope with return address 'Grandma Beatrice' paid for with a single stamp might appear more legit than the same return address paid for with USPS.com and printed with a thermal printer onto a label.
realistically, if the vendors change up the packaging itself semiregualry, it shouldn't really matter whether or not they hand write it.