I would be careful about just sending out low ball offers to just see if they fly. If there isn't a chance it will happen don't waste a bunch of peoples time and risk reputations. A'lot of the time it actually does offend sellers and even the other agent. Your name is on the offer and so is your agents. You can get a quick reputation in your local market like this. I would try to only go after deals that have some sort of chance of going through. Everyone sees MLS listed properties so if you are trying to come in low balling without any signs of it actually working out move on.
I'm super cautious about who I take on as a client for this reason and several others I've had to fire clients although I do it in a way of asking for a refundable upon closing retainer fee of $1500 sometimes higher. I know alot of real estate agents who are the same way most clients look at 5-12 houses at absolute most before they bite on something.
A couple of ideas for you.... try to only look at and submit offers on properties actually with submitting on. If its a hot property low balling or coming in even under ask is wasting peoples time. Go after properties where a seller needs to look at some sort of offer and incentivize the agent saying when I sell the property you are my guy.
I would also try to call FSBO's and start doing more of your own marketing. You will likely gain 10X more traction this way anyways. Everyone and their mom is searching the MLS its just too easy. If you're looking for rentals why not call houses that are for lease by owner and try to purchase them or call management companies and ask if any of their property owners have interest in selling.
When youre a real estate agent alot of peoples walls come up so you being unlicensed and the end buyer goes so much further than a real estate agent calling a seller. Use this as your advantage and target stuff real estate agents don't have listed.
My two cents hope that helps!