Ok, so does that mean that my writing crossovers makes them acceptable to you, or that if I were to write a Dr Who/Marvel crossover you would at least consider it? LOL!
But to continue your culinary metaphor, you are entirely right regarding the idea that some things, abeit enjoyable by themselves, should not be served together. But the chip shop at the top of our road sells Doner kebabs with naan bread as an alternative to pitta, and it's very nice! (This is the West Midlands, and a lot of folk do like naan). I could envisage eating and enjoying curry wrapped in tortillas, or chilli con carne served with Chinese-style fried rice or Indian pilau rice. Some things, though of different origins, can go together very well.
My first crossover was a blindingly obvious linking up of Harry Potter and the X-Men (I called it Xchange Students, which should give you an idea of how dire it was!) My 'best' efforts from that period were a Harry Potter/Sapphire & Steel story and Rediscovery, in which the Enterprise-D accidentally finds its way into an anomaly which proves to contain several planets colonised by Earths' witches and wizards and encounter the descendants of Harry and his friends (and enemies). That one was suprisingly popular!
Later on, I realised that to do the job properly, I had to set up a Storyverse with its own rules and a consistent history. The one I created, the one in which most of my stories are set, has a history embracing Tolkiens' Legendarium, Robert E Howards' Conan, Kull and Solomon Kane, the Alteran Ancients, Arthurian myth, Lovecraftian concepts (the Elder Things, Cthulhu, the Other Gods). Also the Silurians and Sea-Devils. It has JKRs' wizard world and Marvel (mostly comics). It has The Doctor, Cybermen, Daleks, Borg, TimeLords, the Q, Eldar, Dark Eldar, Goa'uld, Vorlons, Shadows, the Federation, Klingons (incuding Klingon Battle-Mages), Romulans, Vulcans, Bajorans, Necrons, Orks and Space Marines. It has CSI, NCIS, UNIT, SHIELD, the White Council and International Rescue. There are Grimms, Immortals and Abnormals.
The Daleks wiped out most of the superheroes and supervillains in 2008. The White Council now works with SHIELD on global threats. Magneto is now Director of Avengers Branch. Colonel Steve Rogers is Director of SHIELD, Harry Potter is Head of Magical Enforcement. A teenage Minerva McGonagall fought Weeping Angels alongside the Tenth Doctor and Donna Noble in 1950s Prague and lost her virginity to Simon Templar in Monaco in the 1960s. Draco Malfoy is a SHIELD agent. Dumbledores' last words - that neither Snape nor Harry heard - were "Hail, HYDRA!". In the grim darkness of the far future, there is only war.
That's how I do crossovers!