If these are 'real' bid jobs, the results ought to be posted, and you would know where you stand.
Since the property bubble burst, I've seen a lot of jobs just 'disappear' ... along with the funding. Other projects are scaled back, drawn out, etc.
Finally, it is a sad fact of business life that there are those who seem to make a hobby of collecting quotes, etc., without any intention of getting work performed.
All you can do is follow up, even ask the customer the reasons for the loss. This is no guarantee that you'll hear the truth, but it's a start.
You also might compare yourself to whoever did get the job. I've known "little Hitler" property managers who would choose contractors on as arbitrary a thing as whether the guy they met was wearing a jacket, or gym shoes.
