The thing with Ali is his best wins are so great that the losses, dodgy decisions and dubious fights can't really impact much on his status. But people shouldn't give him an absolute free pass either. Sure, the Leon Spinks fight was when Ali was far far gone, but at the same time Ali was still the undisputed champion of the world and would have been regarded as among the top 3 or 4 heavyweights in the world at the time even by those who knew he was far gone. Leon was a complete novice and didn't really deserve to be ranked among the top 10, (although I think The Ring had him #9). Of course, by itself the fight doesn't mean much against Ali's whole career. But it's not a loss I can write off completely, due to Ali's ranking at the time. Ali DID deserve criticism for that loss, and he knew it. Losses to Holmes and Berbick I would write off completely.
As for Brian London, I think Angelo Dundee described getting that payday as 'taking candy from a baby'.
Retroactively, this was true, but Ali trained hard for this one, even to the point of sporting a ripped six pack at 209.5 as a byproduct of his work. [One has to look carefully on the B & W HD footage to see it, but his abdominal definition was especially in evidence as he bends forward slightly towards the camera in shucking off his rope.] While boxing is certainly not a physical culture contest, I'm not sure his much commented on muscle tone ever looked better at any weight after 1963. Going in, London was a gimme defense, but also enough of a veteran that he couldn't be taken for granted. Sensible, since Brian would frustrate a young fast Jerry Quarry by remaining on his feet over ten before decisioning Folley the following year. Before the fact, Ali and Dundee were prudent to take London seriously, and an even lighter Muhammad would get extended to 12 in his very next defense, even getting doubled over by a southpaw left cross just before stopping the light hitting Mildenberger. Which could well account in part for Ali's surprising diligence in training for London. Yeah. Don't forget that Brian avenged his 1958 decision loss to Willie on a fifth round cut stoppage later that year. Muhammad wasn't susceptible to cuts like Willie, but they did share much of the same stylistic template. London had been blown out by 'Enery in one, but then went the championship distance in two rematches. Brian had also stayed on his feet through 12 rounds against Ingo [by neutralizing the Hammer of Thor and forcing the Swede to win with his jab], and would have stopped Ingo if that one had been scheduled for the championship distance. He'd also knocked out Rademacher in seven after Pete had acquired some professional experience [enough so to UD Chuvalo in Toronto a few months later]. London was dangerously inconsistent. He could get starched by Cooper, then stand up to both Sir Henry 2X and Ingo. His final career win came over master boxer Folley. Muhammad had been knocked on his arse by Cooper before the London audience, and despite having just avenged that indignity with a rematch, he wasn't taking liberties before Brian was eliminated. [Atypically for him, he didn't raise his arms upon flooring London, but only after Brian was counted out.] Patterson previously knocked London out with body shots, so Ali went downstairs a little bit on him, one of the very few instances we saw this before Cleveland Williams. Muhammad also unloaded a few diversionary hooks later that year against southpaw Mildenberger, but Ali's body punching only ever really carried a fight against Blue Lewis. Despite making a quantum leap from Cooper I to Liston I, Ali was still very much a work in progress until Cleveland Williams. Chuvalo extended him the championship distance, and Mildenberger gave him an opportunity to deal with the southpaw style Machen had just failed to solve [and this was a version of Eddie who would school Jerry Quarry before the year was out, then take Frazier into the tenth before a questionable stoppage in Joe's favor.] For me, Ali was clearly peak for only Big Cat, Terrell and Folley, as Frazier was for only Ziggy, JQ I and Ellis I. However, just as a pre peak Liston was at his fastest and quickest for Wayne Bethea at a less than full strength 204, so too might it be argued Ali's finishing combination on London may have been his hand speed at his very fastest. [He commented during his postfight interview with Cosell that he didn't think he trained as hard as he could for London, citing his previous weight of 201 for Cooper II as evidence for this. But I suspect he sacrificed some strength for Cooper II, and at 204 for Mildenberger. To me, his optimal weight both pre and post exile was clearly 212, as he was for Big Cat, Folley, Terrell, Norton II and Frazier II. To me, he looks stronger at 209.5 for London than he does for either Cooper II or Mildenberger.] Brian London was clearly a more qualified challenger for Ali in 1966 than Leon Spinks was in 1978, and I do believe Leon would still rate as a weaker lineal champ if Ali had suddenly suffered an acute mid round appendicitis attack after the opening bell against London.
Pastrano was considered a colourful fringe to #5 heavyweight contender of the late 1950s. Beating WIllie was a huge win and made Brian London more saleable to America than Cooper was at that time.
Still, beating Pastrano doesn't mean you're not a soft touch for Muhammad Ali. I don't think Brian London was more saleable to America than Henry Cooper. In fact Ali was in England to fight Cooper, and London was just an after-thought.
Nonetheless, Ali did not train for London as if he were a bum, and did not perform down to his challenger's level. Brian was never getting a third shot at the HW title after that. [Nor did he ever want to face Ali again. Kind of surprising he didn't retire at that point, but he still had at least that final win over Folley to prove he wasn't completely washed up for Ali.]
The year Patterson fought brian London he would have been more saleable than Cooper to AMerica on account of beating pastrano. Cooper had not yet beat a rated American so he would be harder to sell at that time. You are corect, by 1966 Brian was not as saleable as Cooper but as a fighting champion there was not much more available to Muhammad Ali with Liston, Patterson and ingo already on the turn. Beyond former champions resume wise Brian London was not any worse than a lot of the then contenders. London beat better names than big cat Williams for sure.
A lot of ink has been spilled over who the best lineal heavyweight champion was, but in terms of who the worst was I think that there is only one answer. A lineal champion has to have a signature win just to get his hands on the title. In the case of Leon Spinks his title winning fight is pretty much his only top level win. There have been other weak lineal champions, but for every single one I could point to some other high quality win. Try me.