More buyers should do a bit of legwork before viewing properties - get mortgage offer in principle or get their evidence of funds sorted out, get all their ID paperwork photocopied etc, obviously have a buyer on their own property if selling (and have paperwork ready to show about how far that has proceeded). I wouldn't be showing the EA evidence of funds etc before making offers as you do t went them to know the limit you can stretch to, but telling them you have it all ready and sending an email listing all the documents you will be able to provide instantly an offer is accepted is a a good move.
EAs often distinguish in their minds between buyers and put forward prospective buyers in different ways to the vendor. So in the EAs mind, there is the time waster, the very green and unprepared buyer who might never get a mortgage or sell their own home, the one who is keen but disorganised, the one who is keen but probably faces a number of obstacles, the one who is ready to proceed with a buyer and a mortgage in place, the one who is ready to proceed with a mortgage in place and no need to sell anything, and the cash buyer who is ready to proceed and has nothing to sell.
You can't usually help if you need to sell or need a mortgage, but you can show you're ready to proceed and out yourself in the strongest position, so that the EA is favourable in their recommendation of you to the vendor and you trump others in a similar or possibly even better situation.