There are obviously some bad experiences of partnerships on here!!!
To say they are dangerous and only work with best friends or sisters is rubbish! It's like saying marriage doesn't work! Well for some, unfortunately it doesn't, but for most it works perfectly (with plenty of effort from both sides!!)
The best piece of advice you've been given so far is to go with your gut reaction. If you don't feel right about it, don't. But to dismiss a potential successful partnership business because they 'don't work' is not the right reason.
I was in a business partnership for years when I first started out in nails and it worked perfectly; I'm in another one now (and I've been married 25 years). It just takes the right partner and the right legal deal (plus a lot of work and a lot of trust)