Loughran actually fought a much better list of opponents than Louis, who was one of the exceptions to the rule.
Pipino Cuevas. Picked up early losses, then hung around too long. In his prime he was a very good welterweight. won 35 (KO 31) + lost 15 (KO 6) + drawn 0 = 50
Humberto Soto is 46-7-2 but he is one bad dude. Most of his losses came early in his career. He needed money at a young age so he took on more than he could when he started. He payed the price with those defeats on his record. But he can scrap!!!!!!
Along those lines there's also Matthew Saad Muhammad (39-16-3)and Dwight Muhammad Qawi (41-11-1). This thread would be better specified when considering either current fighters with poorer records who are still fighting at a high level or past fighters who were still successful around the time of their excessive losses. Fighters who racked up a bunch of losses toward the end of their careers are far too many to name.
There are lots of fighters that aren't accurately represented by the seemingly large number of losses on their records - most of them are the hard-working journeymen that get in the ring day-in and day-out with young up-and-coming prospects or to give beltholders tune-up or stay-active fights. Dudes like Sedreck Fields and Ross Puritty whose resumes read like a who's who of the heavyweight division. Even guys like Reggie Strickland, widely mocked as the worst boxer in history, aren't bad fighters. His job isn't to get in the ring and win, it's to provide an opponent and to give guys rounds. In over 250 losses he's barely been stopped in 1/10th of those. He's good enough to not get hurt, and to box for 18 years for almost 350 fights. I respect that regardless of what his ledger looks like. Glance over his record at Boxrec sometime and see how many names from lightweight up through super middleweight you recognize. Probably quite a few.
Michael Domingo won 37 (KO 16) + lost 14 (KO 5) + drawn 2 He caught hepatitis B just before he got his title shot after beating Ratanachai Sor Vorapin.