You seem to have a healthy arsenal of RE questions.....Are you by chance a disguised trulia staffer or just curious?
To the question.....I personally have made a blind purchase that worked out well for us but I wouldn't recommend it as a practice for newbies.
My client will typically base the "rehab" amount dependant upon pictures for a rough estimate and we work our numbers out that way. I do this type of offering for a majority of my investment clients and it is the only feasable way of getting enough properties under contract within the time provided unfortunately.
Our success rate of actually going through with the offer is about 85% (we typically pull out if the rehab is just an insane amount). If there are no interior pictures and I don't have time to go by myself first, the general starting point of the offer is lower. I think it works great if implemented correctly. That is, if you don't abuse it of course!
Success depends on the property type and your market conditions. If you're listing a condo in a hot market, then there are plenty of savvy investors who don't need to see the property before getting into contract. I've deal with plenty of those buyers from the listing side who have closed quickly without a fuss.
If you're listing single family homes, then it makes more sense to require a viewing since home buyers are more typical and they're more selective about little details like views and floor plans.