On the whole, 'Scooby Doo and Scrappy Doo' is one of the weakest of the Scooby Doo shows. It did though have a very watchable first season, with the best episodes actually being very good and only one episode being below average. After the first season, the show very quickly went downhill and never really got better despite some watchable shorts here and there. Shaggy and Scooby were always the most interesting characters and didn't mind that they were main protagonists, did mind though that the other protagonist is one of the main reasons as to why Season 2 onward did not work.
Unfortunately, "Scooby's Bull Fright"/"Stow-Aways"/"Long John Scrappy" is another not particularly good triple bill, always thought so as a child and my feelings are pretty much the same. It has its moments, primarily in "Scooby's Bull Fright". But there is too much that is wrong, with a lot of what is wrong with the show in general present. With "Long John Scrappy" being a missed opportunity somewhat. None of the shorts are unwatchable, all three are nothing special as well.
There are definitely good things here. There are a few good moments, with the best parts being the penalty box gag in "Scooby's Bull Fright" and the genuinely scary jump scare with the shark in "Stow-Aways". The bull is a fun character and suitably antagonistic, better than most antagonistic characters for this period of Scooby Doo.
Voice work from all involved is spirited on the whole, Casey Kasem and Don Messick are great as Shaggy and Scooby. Have always liked the theme tune, which is catchy.
A lot is wrong unfortunately. The animation is very rushed looking and flat with very irregular character designs. The music is nice on its own but doesn't always gel with the action, some of it on the repetitive side. Good gags are too far and between and most of the too few that are there fall flat from feeling too rehashed and predictable, as well as really corny. "Long John Scrappy" is pretty much humourless, and the heavy emphasis on Scrappy (who is as one would expect) dampens the enjoyment.
Did find all three stories very thin and repetitive, as well as too past prime Tom and Jerry-like. Especially "Stow-Aways", which is completely forgettable other than the aforementioned jump scare. No excitement or variety in any of the running around action, which is present in all three shorts. "Scooby's Bull Fright" worked a little better than the other two, because at least the bull was a good character. The pirate character had potential, but actually would have worked better as a ghost pirate as he came over as too ordinary.
Furthermore, Scrappy brings things down significantly, especially in "Stow-Aways", he dominates far too much to the point where it feels like he is the main character and even more of a problem is that he is also incredibly annoying. Due to negative character traits (namely arrogance, over-zealousness and being pushy) being exaggerated, his behaviour and catchphrases already being incredibly repetitive and his ability to make things worse rather than better by putting Shaggy and Scooby in danger with little remorse or mistake acknowledgement. Messick is great as Scooby, but overdoes it as Scrappy. Shaggy and Scooby have moments, especially Scooby in "Scooby's Bull Fright", but play too second fiddle to Scrappy.
Concluding, has moments but pretty lacklustre. 4/10.