reph said:
I can see a case, sometimes, for inserting present tense in a character's thoughts when the narrative is otherwise in past.
I woke up with a start. The room was dark, the TV still on. I must have slept through the end of the movie. I put on my glasses and saw a man in an apron demonstrating some flimsy-looking cookware. Oh, one of those dreadful infomercials that you get in the middle of the night when the real programs have stopped. What time was it, anyway? I got up...
That's a little better use, but it's there to show an ongoing action or process, past, present, and probably future. It isn't really a true blending of past tense and present tense. I would say that "have stopped" isn't even present tense at all, but "past continuous" tense.
"Have stopped" means something has already stopped, not that they are stopping in the present moment. The shows have stopped, and at present the infomercials are on. The process, however, is ongoing, which means the use of "get" is acceptable, and the past continuous of "have stopped" reinforces this.
But it really isn't a blending of past and present. It's continuous action, past, present, and future. Continuation, not simple grammar tense of past or present. Ah, probably too British of me.
And even doing it this way,
Oh, one of those dreadful infomercials that you get in the middle of the night when the real programs have stopped reads poorly to me. I can't see any possible need for it. Again, it jolts, though only partly because of the tense. To me, it doesn't read to me like narrative.
I think teh right way to write such a sentence is to start it as past tense, which makes the ongoing "get" work much better.
Oh, it WAS one of those dreaful informercials. . ." This works, doesn't jolt, and makes all the narrative read as narrative. Consistency.
I think such writing can be used to show an ongoing process, an action or event where time is meaningly, something that happened to you last week, this week, and may happen tomorrow, but I still think you have to tread very cautiously, and past should be past, present should be present, and blending the two should be done with extreme caution, and then usually discarded.