Okay so I know that everyone says ready meals are bad for you but I wondered why?

I, like most I imagine, go for the quick and easy option when I get home from work late, so I always have a few stored away.

So are they bad for because they are full of salts and preservatives, because there is low nutritional content and do they stop a general diet working?

I like the curry dishes best and I hear that a lot of the Indian spices are good for (Waitrose ready meal sale ) so are these okay?

I think they're OK in moderation. A quick look at the ingredients will tell you have many additives are included. I think many are well made. Obviously the lower fat ones would be better for weight loss so the tomato based curries are more diet friendly. Alternatively, you could make a whole pan of curry and freeze it in portions. Then you know exactly what you're eating.

The main issue with them in terms of fat loss is the high calorie content.

Having said that, as long as you're at even a marginal calorie deficit, having the odd ready meal should be fine.