Should that be something that should be avoided when trying to get stronger? I have learned, in order to gain strength, it's all about building and not testing.
Not necessarily. If you are always working up to a 1 rep grinder, yeah you should probably not do that so often. If you are working your reps and get to a point of near failure, I don't really think that it is a bad thing.
The structure I am running is hard work, and some of the sets are occasional grinders towards the end, but I feel this is more to do with the volume I am running over the numbers I use. As Big Chris F has already stated, within the confines of a program, I don't think it's a big deal, so long as every rep isn't sloppy. An example is the fifth rep of my 5x5 80% benching has been slightly off during the last couple of sets, (slight arse raise or a slower press), but it is more general fatigue over a strength issue. When I have gone for one rep maxes each week, such as when I was practicing hook gripping my deads, I found I would actually get worse at the lift as the weeks progressed. Focusing on repping out at 80-95% has been more beneficial in bringing up my strength than constantly grinding out heavy singles and losing form trying to chase numbers.
I grinded alot of my lifts in the last weeks of my meet prep last year, and that ended up being my best meet to date. It prepared me to really grind (final squat took me about 6 seconds to stand up) on the platform... I suppose that's not good to do alot, but imo some grinding is good in training. I've seen ppl who can't grind out a lift, they just fail as soon as it gets heavy and that's it. I'd rather be used to grinding and be able to use it on the platform.
I've really become pretty wary of grinding out shitty reps with any regularity, especially concerning squats and deads. While its definitely important to push yourself hard, I just find that with tough reps form is a lot more likely to go to crap, and thus the chance of injury skyrockets.