Not to be pedantic, but … if the forcefields were invisible, how would we know there weren’t any? 
On the other topic … yeah, Feds do seem to be pretty naive when it comes to things like contagious diseases and highly prolific wildlife.
They actually did appear in, of all things, the animated series. But the main television shows never put them in and treat them as a non-topic. The few times anything like that show up, they were jury-rigged and very brief.
Doesn’t the use of transporter basically prevent the infestation of wildlife? You’re only beaming up the molecules of that person.
Apparently not with tribbles… :eek:
That’s the trouble with them. :dubious:
If you’re referring to diseases transmitted by wildlife, there was a “decontamination” protocol in place for use after beaming up, but it was implemented only once that I recall (“The Naked Time”). In TNG, of course, the transporter had biological “filters,” which apparently didn’t work too well either (at least for Dr Pulaski).
Above, I was referring to animals with tremendous multiplicative proclivities. 
In that TNG crossover Tribbles episode, when someone commented that the Klingons from Picard’s time didn’t look like the Klingons of Kirk’s time, Worf said Klingons didn’t talk about it and gave quite the glare at the commentor. So, I guess it was a Noodle Incident.
They later explained it in the prequel series. It was… meh.
Yeah, but they addressed that in-show by turning Delenn into a Mimbari/Human hybrid. A better example would be a certain non-human warrior in the show’s predecessor.
What’s weirder is the opposite, when someone on a prequel show finally gave a shit and fixed a certain female alien’s eyebrows.
That was DS9, Trials and Tribble-ations. They do eventually give a hare-brained explanation in Enterprise: the Klingons were experimenting with Khan’s human augment technology and yadda yadda yadda bumpy foreheads.