Tommy, is 「さぼる」the same as 「サボる」?

Yep. ^^
Although it comes from the french word "sabotage", it's so often used that I don't feel it's a foreign word any more. So I prefer writing it in hiragana.

Interesting. :-) Is there a tendency to start writing borrowed words in hiragana once they become very popular? :-)

Even if a loanword has become popular, we don't write it in hiragana if we feel it's a borrowed word. For example, パン (which derives from the Portuguese "pão") has been used for more than 400 years, but it's seldom written "ぱん" since many people know it's of foreign origin.

In the case of "サボる", the sense of foreignness is weakened. It's partly because it conjugates as if it's a native Japanese verb, unlike most borrowed verbs such as "チェックする" or "シュートする". Another reason is that the French word "sabotage" is not familiar to us. Most of us know "トラブる" and "パニクる" come from English even though they conjugate like an original Japanese word, because we know the English words "trouble" and "panic". This is not the case with "sabotage", I guess.

There's another reason to write a word in katakana. We sometimes use katakana to write slangs, even if it's a native Japanese word. For example, "キレる" in the sense of "get angry" is rarely written "切れる". "サボる" sounds more or less slangy, too, so this might be another reason that it's often written in katakana. However, I personally feel it's not too colloquial or vulgar, so I feel like opting for hiragana.

Thanks, Tommy, now I understand.
By the way, it seems that in Japanese borrowed verbs are not as common as, say, borrowed nouns. Does it mean that you're trying to not "poison" Japanese with foreign verbs?

Maybe... I'd never thought about that.
Borrowed adverbs and borrowed particles must be even more rarer. I wonder why... It's an interesting theme!