Have you ever seen haggis?

As for the exo-bacteria and viruses, I don't think we have much to worry about diseases from alien micro-organisms, for the same reasons I listed about the digestibility of alien meat and veggies--they would not be chemically compatible with us.

Disease-causing bacteria and viruses are highly evolved parasites that target very specific organisms; organisms which are constantly evolving defenses against them. How many infectious diseases are humans vulnerable to, even though there are hundreds of thousands of microbes on earth? Only a handful of infections can jump the species barrier, most attack only one, or at most, several closely related species. The idea that a foreign bug could get a foothold in our body, with a totally different biochemistry and a separate evolutionary history, is highly unlikely. Of course, it would be foolish not to take precautions, and run some tests, but I believe the dangers have been highly exaggerated.

A much greater danger would be chemical poisons that the aliens might find harmless, but which might be deadly for us. I remember an Asimov short story where explorers land on a planet and suddenly start experiencing strange and unexplained deaths. The culprit is finally tracked down--it is beryllium in the soil and water, in miniscule, but toxic (for humans) concentrations. The astronauts no longer tested for it because it was long banned for industrial use on earth since it was poisonous, so its dangers had been forgotten. I understand tellurium is another one, it is so rare and toxic in such tiny quantities that a few clever murderers used it on their victims and were getting away with it until the cops got hip to it.

Suppose our aliens were vulnerable to nylon poisoning, or reacted violently to garlic exposure? Hell, we're probably killing ourselves by the millions with our own industrial and household chemicals without even realizing it. Ya never know.