Hi, redisme, and welcome to AW.
It's usually a good idea to research agencies before submitting to them because it can save you a lot of heartache in the long run.
As has been said on the other thread here, JLA is listed as not recommended on P&E on the basis that it charges fees and having done a Google search I can't find anything about them that would either change that view or offer sales credentials as an agency.
There is no such thing as a stealth agent and it's better to have no agent at all than to have a bad agent.
Incidentally - this shouldn't be confused with JLA, a London agency that specialises in after dinner speakers and performers and has a v. impressive stable of clients.
MM