Colin
Here is some examples of the quality ones I use in Perthshire.
thebunkhouse
Adventurers Escape
Culdees
This one is not on my patch but it is good
Comrie Croft
From a business perspective you need high occupancy rates to make these pay well. The price per person per night is low so it is all about having bums in beds on a very very regular basis. A lot of the ones who are making real money combine the hostel with another business and you create multiply income streams.
Ideas of top of head
Guided tours of Perth
Bike Tours of Perth
River Tours on the Tay
Tap into the new concert hall it is getting big name bands on a more and more regular basis and tickets can be expensive so people may want a cheap bed when they are in town.
Perth is hosting more and more conferences each year. With these you could get whole hostel bookings. Not suitable for every type of conference but will work for some.
Scone palace tours
Perth Race course packages
I could go on but you will get the idea
peter