If there were such a risk with takiing a hydrometer reading then why do you think every book, video, and forum advocates using one?
You know, there is so much telling brewers, what not to do,
do you actually think folks would be saying to use your hydrometer so much? Is it a vast conspiracy to ruin millions of new brewer's batches, so that they flee the hobby and give it a bad rap?
Using basic sanitization, taking a hydrometer reading is no risk at all.
This is what I use, and it works with both buckets and carboys
Here's what I do....
1) With a spray bottle filled with starsan I spray the lid of my bucket, or the mouth of the carboy, including the bung. Then I spray my turkey baster inside and out with sanitize (or dunking it in a container of sanitizer).
2) Open fermenter.
3) Draw Sample
4) fill sample jar (usualy 2-3 turky baster draws
5)Spray bung or lid with sanitizer again
6) Close lid or bung
6) take reading
It is less than 30 seconds from the time the lid is removed until it is closed again.
Probably less if you have help.
And unless a bird swoops down and poops in your fermenter, you wont have any trouble.
So grow some stones little soldier and use it!!!!!!