Mostly I've had good guacamole but I do remember the Bad Guacamoles, too, and I can characterize them easily: too much stuff.
Bad guacamole simply has too much stuff in it: onions, bacon, cheese, hamburger and other junk.
Just. Say. No.
Guacamole is best simple. Mashed avocado with a few spices, perhaps a little chopped tomato, cilantro and plain yogurt or sour cream if the avocado is too dry. Salt, of course, and maybe a dash of chili powder. But that's it! Don't try to be a guaca-hero!
Here's my guaco today. Avocado, plain yogurt, a chopped slice of tomato, garlic powder, dash of cumin powder and salt. Done and done. Served chilled with chips and bask in the glory of appreciation.